This 50-50 split has been my reality since my X moved out in September. My kids (all boys) are 11, 7, 4. I had always done everything for the kids in terms of caregiving and nurturing. He played catch or football with them and sometimes took them fishing - that kind of thing. But I did everything else. Of course, in his messed up self-centered mind he may actually believe he did 50% of the caregiving/nurturing. The minds of men who have an unhealthy amount of narcissism are messed up and defy logic. They are ruled by a sense of entitlement and are incapable of empathy. They twist reality, the past, whatever they can to make themselves look good. But this is a bit of a tangent, I'm sure you know this well (sadly).
I live in Canada where 50-50 is the standard unless a parent can prove the other cannot be a 'good enough' parent. 'Good enough' is the basic criteria for 50% - and it takes pretty basic parenting to meet that 'good enough' qualification. To prove he is not 'good enough' and thus not worthy of 50% will require a legal evidence such as a DUI, etc. That was the hardest for me to swallow. I know and you know our Xs are not up to the task of being the kind of caretakers for our children that we want them to be. The hard truth is that I have to let go of his share. He gets them to school, they get some sleep (although far from enough), they are fed (sugar and disgusting processed junk, but their not starving), they are clothed, and every now and then he bathes them. He doesn't do storytime, or have set bedtimes, or gives them fruit for snacks. His mom (who you can imagine is just as messed up) comes from 3 hours away every week when he has the kids and sleeps on his couch to do all his housework, etc. If she didn't come, he would get a nanny/babysitter and I would have to accept that (I would actually prefer it, but I have no say because it's his time). And then there is the manipulation/alienation.
My ds1 is so messed up from growing up in an abusive household (X abusive to me, in front of the kids and to ds1) that it has only gotten worse since the separation. He is extremely violent and aggressive toward me. But other times he reveals he is so tormented and fearful of becoming like his father and he loves me and is so gentle and compassionate. So, I had to get interventions to help. X blocked my attempts to get help and I had to take him to court to get court-ordered consent to begin the process of getting us emotional/psychological support. In this process, the court ordered a parenting/custody evaluation. If you have real concerns about your X's parenting (abuse? manipulations? substance use? etc.), I recommend you get one of these evaluations by a recommended forensic child psychologist - someone known to be fair and just. The process is extremely invasive and frightening and beyond stressful (you can read through some of my old posts to get a sense of the torture I went through) and ridiculously expensive ($13,000 for us, but most resources online say they are usually between $5,000-8,000). The outcome didn't change the 50-50 arrangement because X lied about everything and the kids were too scared to tell the truth. BUT, the evaluation report did reveal that he is not a credible reporter of what goes on in his home. It did state that he was abusive and has an 'impoverished understanding of the negative impact he has had on his wife and children' and it did say that the concern is that the boys will grow up and when they find themselves with power in a relationship, they will act in the way they have been modelled by their father. It did say that ds1 is acting out with me because he grew up seeing his father treat me as though I am an object not worthy of respect. It did say that he is egocentric, impulsive, angry, irresponsible, emotionally-shallow and seems intent on pathologizing me. Even with all those statements, it remained 50-50 because there was no evidence that he is abusing the children, that he is manipulating them (they were too scared to tell), that he is drinking (he simply told the psychologist that he doesn't drink at all), that they have set bedtimes, etc. BUT, that report is filed in court. So at any point when something is wrong, my concern will be addressed and considered because he is not considered to be credible, reliable, etc. So, that's a really good thing.
Now, onto the reality. The point I'm at (and it's a long long journey, so expect to feel like you're guts are pouring out of you for a while first) is acceptance and trying to stop being affected. I know what I ahve to offer my children. I know I offer them love, stability, nurturing, good food, sleep, peace, structure. He will give them fun times and make my parenting so much harder. But it will be so much better than before we separated. I use their time away to get everything ready so all I have to do is focus on them and play, etc. when they are with me. I am there for them. I give them a stable, loving home for 50% of their time. When they get old enough they will be able to choose to stay with you more. I have actually really really needed that 50% of my weeks to begin the healing process, and before I could even begin to heal I used that time simply to cope and get through the weeks and months.
From your description, he will not be kind to you. So, as soon as this starts, you must cut phone communication and texting. Use email only and limit it as much as possible to only details about the kids. Use your lawyer to get all the parenting details into a parenting agreement and to communicate the divorce/property stuff. Do NOT care about him. Sounds like you're past that anyway.
As for the kids, it will be hard. They might cry and not understand. It will be a big huge adjustment for everyone. Make sure you tell them that even when they are not at home with you, you are always thinking of them. And tell them that when they are going to bed at their daddy's, you are thinking of them and blowing kisses and whispering goodnight to them. You can send them with a special stuffed animal that you get special for them. When they are with you, listen to them and acknowledge how hard it is. Tell them their daddy loves them and that you love them and you both will always love them.
When we told our kids, our 7 yo burst out sobbing and heaving. It was very traumatic for me, but then I realized what had happened - he thought it meant that we would leave this house AND they were going to have to get a new mommy and daddy. As soon as I realized this and clarified (about a minute later), he stopped crying instantly, lol.
Here, I have been told that there is no way a judge would allow my X to move out of the area unless he wants to give up his weekday parenting time. Depending on how far it is, that is likely for your X. My X has been talking about moving 50mins away from their school. Not happening!
On a really good note, my kids are doing awesome (except for ds1, of course, but he was really troubled before and had been seeing a psychiatrist for 2 years already). Ds2's teacher has told me from the beginning of the school year (which is right when X moved out) that ds2 is very happy, gentle, very popular, laughs a lot, listens very well, and works very hard. She noticed nothing of concern and she is a very good and experienced teacher. Ds3's daycare has reported no changes or concerns at all and have nothing but glowing reports about him - funny, fun, popular, cuddly, a real joy to have. So, as much as it is not how I want my children to be raised (eating junk 50% of the time, watching TV for hours a day 50% of the time, listening to their misogynist father gossip, etc.), they are doing really well.
I have a family counsellor who comes to my home once a week (appointed by the Ministry for Children re: ds1) and he uses the metaphor of planting a garden. He said that when you live in your house according to your values and your principles, you are planting seeds in your children's gardens. He said, you never know which plants will grow (ie. you can't control who your children will become and what will be important to them) but you know that some of those seeds will grow into mature plants. So, I'm working on being very clear about my 'philosophy of life' and living by it. Like I said, it's hard because so much of what X does sabotages my way of living, but I will no longer let him tell me how I should raise my kids in my home.
That was a real novel and probably not as warm and fuzzy as you would have liked. Perhaps I should have been more gentle. It will be ok. Your kids will be ok. They will no longer see him walk all over you. You are showing your children that you are worthy of respect and you demand to be respected. You are teaching them A LOT by separating. What you are doing is so utterly brave yet frightening. No longer will you put up with less than you deserve and they now have a beautiful, strong (although I know you don't feel like it right now), loving, peaceful, powerful role model for their mom :)
You can do it! Post here whenever you need support. It's a painful journey - more painful than I could have ever imagined. I was with X for 15 years, you for 20 so you must give yourself lots of time to heal. It will not be quick.