*I could be totally off base here with inexperience (so please no one flame me).*
My 11 year old DSD can be much this way, minus the rages (although I think she rages at her mom's). She can be emotionally manipulative, say very cruel things, be dramatic, excessively jealous, etc. She is coming to live with us full time in less than a month because her emotional needs are currently not being met. (Please understand I am not saying that anyone here is not meeting their child's emotional needs. I am only stating what is going on with DSD.) She requires a lot of attention and tends toward regressive behavior when she isn't the center of attention. I love her very much and want to work with DH to help her to grow into an emotionally secure young woman. These are some of the things we've done/plan to do when she arrives to live with us. Many of them have been proven to work with her during summer long visits.
We give her attention. Usually when she's pushing my buttons, I talk to her about what she needs from me. She has told me that sometimes she just needs to talk to me about nothing in particular. I responded, "So you need my attention?" I told her it was perfectly okay to need someone's attention just to talk, that sometimes I need to talk to her dad, about nothing in particular, just to talk. I let her know that she can ask for my attention anytime and that I will make time for her. She said, "But that would seem DESPERATE!" I'm working to help her identify her emotional needs and to talk about them with us.
I had DH start Dad/Daughter dates. She LOVES these and always looks forward to them.
Likewise, I take her out--just the 2 of us for a coffee date. The baby stays home with DH and she has my full attention. She's content to sit at the table and talk for a few minutes, to spend a chunk of time writing separately and to share what we've written at the end. But she has *me* all to herself during that time.
I praise her often. I tell her what a great job she's doing/has done/etc.
I involve her in the care of her younger brother. She loves to pick his pjs out every night (and once became very emotional when she couldn't pick out his pjs due to extenuating circumstances). She loves to read DS bedtime stories and 1-2 nights a week will be her special time to read to him. If she asks to change his diaper, I allow it, while letting her know that it is not expected of her.
Meanwhile, she can be very jealous of her baby brother, as well. I am very careful to balance the attention I give.
We talk with her at great length regarding her emotions and help her to process them. We help her to define her needs and to seek direct ways of getting her needs met.
I suggested to DH that he can read DSD a bedtime story, maybe a chapter from a chapter book, etc. I know that she will LOVE this and that it will help her to feel secure emotionally.
We plan (for a variety of reasons) to homeschool her (at least in the beginning). But I think the 1:1 individualized plan may be just what she needs.
We give her/encourage her to seek attention in developmentally appropriate ways. For instance, DS was getting attention at the dinner table, DSD became visibly upset/sad and asked if she could show us how the piggies eat. At that point, I redirected my attention to her and asked her to talk to us about something she was involved in, a project, an interest or what not. This way she is getting attention in a developmentally appropriate way and not resorting to regressive behavior.
When she gets a good deal of attention, she thrives. She's creative, imaginative, emotionally intuitive, is a great big sister, a good little sister, is sweet and affectionate. ... And when she regresses emotionally regarding her behavior, I ask her what she needs from me at that moment.
I realize our situations are different, as DSD has not been raised in an AP home. We AP her when she is with us and will parent in that style going forward. It sounds like you've already been parenting AP style. Best luck to you. I just wanted to toss some of what has worked for us out there, along with some things we plan to try when she's living with us.