How scary to have your daughter be so violent that you felt you had to lock her out of the house! It makes perfect sense that you did that, because you did not know how else to keep everyone safe. But I suspect that it triggered all of your daughter's separation issues and contributed to a scary cycle. I'm glad you wrote.
No, fits of anger that last for two hours and include physical assault are not normal for a 7 year old. You are right to be concerned. So the question is, what is going on, and how can you help her?
I think your daughter's baby talk, which preceded knowledge of her brother's birth, is a clue for us. Something went wrong back when she used baby talk, and she is trying to tell you about it and get your help with it. It was after she became verbal, but was still quite young, and your description of her separation from you at age 2.5 for two months sounds like it is almost certainly at the heart of her behavior.
Toddlers who are separated from their trusted parent and left with someone they don't know well --even the other birth parent-- can be expected to have a major reaction. (John Bowlby, one of the fathers of Attachment Theory, had a lot of experience with babies separated from their parents during WW2, which was a major contributor to his understanding of Attachment disruption.) If you had left, and she had been with someone she loved and trusted, she could at least have cried and raged about your absence, and felt that someone who loved her was there to listen and understand. But she not only had to experience the grief of your absence, which to her was just like a death. She also had only a near-stranger to care for her. She must have been terrified but unable to express it. And she never got a chance to work out these terrible feelings, she just locked them up inside. Once we feel our big feelings, they evaporate. But until she does, they will gnaw at her, overwhelm her, get triggered, and drive her to lash out.
So I think what is happening is that at times your daughter gets triggered, and relives those unbearable feelings of grief and terror that she felt at age 2. At that moment she feels like she is two years old and abandoned by her mother and in danger of dying. This terror is so unbearable that she lashes out. (The best defense is a good offense.) Aggression stems from fear, and her terror is so acute that she moves into fight or flight, and everyone around her, even her beloved family, looks like the enemy. If she can just hit something, break something, maybe those feelings will go away.
When this happens to her, it is almost as if she moves into being a two year old again. Afterwards, it seems almost like a dream. So her description of her meltdown as a dream sounds eerily accurate. What she is telling you is that it wasn't really her, it wasn't even really real. But of course her rage is real, and can really hurt.
You are right that you need to help her work this out now, before she gets any older. Otherwise, she could indeed hurt someone, and that would be devastating for her (as well as for whoever she hurt.) I think she also needs to feel that you can "contain" her rage, or she will become even more frightened.
Yes, it is possible for you to do some play therapy with her. It will help a great deal if you can first journal or talk to someone you trust, just to vent a bit and work out some of your own feelings about this incident five years ago. If you are still feeling guilt and grief, it is harder for you to be there for your daughter. It is true that you cannot undo the past, although I know you would give anything to do so. But you can, and must, grieve about it to let it go. So do your own crying first, so you can be there for your daughter's grief. Otherwise, it will just be too upsetting for you, and she will get that message loud and clear.
Next, build trust. I would begin by finding 15 minutes to half an hour daily that you can spend only with her, when someone else is with your other children. Use that Special Time to connect deeply with your daughter. Invite her to be your baby. Feed her a bottle of water. You can also pretend to nurse her (through your clothes is fine, it's a pretend game), if she prefers that. Let her use baby talk and be a baby to her heart's content. Play "baby games" with her like "This little piggy." This will fill a deep need for her. If she giggles, all the better, because it means she is releasing anxiety about her wanting to be a baby. It may also trigger her big issue, maybe not the first day you do it, but eventually.
You can also build trust by reassuring her that you love her deeply, no matter what. Not in words, but with a game. One of my favorites is the Fix game. (Substitute her name here.) You play the bumbler as you chase her, hug, kiss, let her get away and repeat again and again: "I need my Chelsea fix....You can't get away...I have to hug you and cover you with kisses....oh, no, you got away...I'm coming after you....I just have to kiss you more and hug you more....You're too fast for me....But I'll never give up...I love you too much...I got you....Now I'll kiss your toes....Oh, no, you're too strong for me...But I will always want more Chelsea hugs....I'm coming after you..." This game is guaranteed to transform any child's doubt about whether she's truly loved (and any child who is "misbehaving" harbors that doubt, which is why she says that she's stupid and ugly and hated.)
I would also suggest, sometime when you have a little extra time alone with her and another adult with your other children, doing some play acting with stuffed animals. Have the mother teddy bear tell her little one how much she loves her, but that she is very sick and the baby needs to stay with daddy for two months. Have her say goodbye and leave. Have the baby flip out and sob and rage. (You should decide whether you to use a father bear; I assume he should be present but ineffectual.) Your daughter will probably watch with great interest. If she expresses any feelings, reflect them: "You are so mad at that mother bear for leaving."
At some point, your daughter is likely to responds to the teddy bear play or the baby play or a separation situation or simply one of life's travails by getting very angry. Hopefully, all your baby games and teddy acting will have laid a foundation so that she is able to get past the rage that is defending her to that more vulnerable terror and grief underneath. Also, hopefully, this will be at a time when your other children are safe with another adult. You can actually orchestrate the timing you desire by finding a time on the weekend or whenever another adult is there, and triggering a meltdown. Maybe that is the time to do the teddy bear play. Or maybe your daughter is in a very ornery mood and nothing is making her happy, which is a signal that she needs to get some big feelings off her chest. Set a clear, kind limit on her unacceptable behavior, and she will almost certainly have a meltdown. That's a good thing, even if it feels scary, because it's an opportunity for her to unload all those feelings that are making her so unhappy. And you would rather have this happen when you can give her your full attention, while someone else keeps your other children safe.
When your daughter has her meltdown, keep yourself safe, obviously. But stay as close as you can safely stay to her, and keep a verbal bridge with your girl by telling her that she is safe. Remember that she needs you to let her express those big feelings so she doesn't feel so alone with them. She doesn't WANT to feel them; they are terrifying. But with you there, she can be braver and let herself face what she couldn't face when she was two. So let her cry and rage, and keep reassuring her that she is safe, that you will keep her safe. Tell her you know she was so scared when she was two, and you are so sorry that you couldn't be there for her.
Just so you are prepared, when children express old fears, it often comes out as writhing and sweating and getting flushed. She may shake and yell. She may want to struggle against you. I don't recommend holding children against their will, and of course you should not let her hurt you, but it is fine to say "You want to push on me, Ok, I will hold this couch cushion, and you can push on it as hard as you want." This kind of fear and anger can be scary for parents, so keep breathing and reminding yourself that she needs a witness for these feelings. Thank her for sharing them with you. Tell her that you will never leave her again, that you are so very sorry, that you see how scary it was for her.
Your daughter might go right into her big feelings. She might get very angry and yell at you that you're a bad mother. She might simply wail and beat on the rug. Whatever she does, just tell her you see how upset she is, and you are right there and will keep her safe and you aren't going anywhere. If she yells at you to go away, tell her you will step back a bit, but you won't leave her alone with these scary feelings.
Of course, she might laugh a lot and skirt around her feelings. That's fine. That means she doesn't completely trust your response. After all, last time she went into these feelings, she got locked out of the house. Remember, laughter releases the same anxieties as tears, so if she makes a game out of any of this and laughs about it, go with the giggles. She's establishing trust. Just keep bonding, accepting whatever feelings she shares. You don't need to force anything. Trust her to find her own way to heal herself, once she gets the message from you that you are fully available for that process.
When she turns hateful, whether during your play sessions or any other time, acknowledge her anger. Again, your goal is to get to the upset under the anger. When we respond to an angry child with complete compassion, our child often collapses in tears, because it disarms the defense. So if she lashes out, breathe deeply, center yourself, and stay as kind and calm as you can. Say "Sweetie, you are so angry. You must be very upset to speak to me that way. You know I don't speak to you that way." (Of course, if you do, it's time to stop, for many reasons, not the least of which is it gives her permission to act that way to you, and it keeps her from feeling safe enough to show you her deeper feelings.) She probably doesn't even know why she is triggered. If she yells that you are being unfair, or you love her sibling more, or she is ugly and stupid, or you hate her, just stay calm and reflect the deeper feeling: "You are so angry and upset....You feel so mad at yourself and at me....You are so unhappy...." Reassure her that you are right there, and you love her, no matter how angry and upset she is.
I am hoping that these suggestions will work for you. If not, I urge you not to wait, but to seek professional help for your daughter before she gets any older (and bigger.) If you end up doing that, please don't let her be labelled and/or medicated. She almost certainly will respond to play therapy that allows her to surface this early trauma and work through it, or to family therapy that includes you. A therapist who does healing work around attachment issues may be perfect for your daughter (but ask specifically if they ever advise holding a child against her will, and if so, find a different therapist.) And I suspect that you won't need a therapist, if you can do this major healing with your little girl. The truth is, the healing is for both of you, and for your relationship.
I wish you and your family every blessing. Please let me know how this unfolds for you.