Sancho, yes waking mid REM, people can experience what's sometimes referred to as sleep drunkenness. Studies have shown, for some it may trigger mood disorder that leads to day time depression, low self esteem...… you get the picture. Does your DD ever talk, complain about her sleep, that she struggles sleeping well, dreams prolifically, disturbing dreams?
You posted this in another thread, I can imagine your DD feels this regularly.
One thing that helps me sometimes is remembering a couple of occasions usually when we are driving somewhere as that seems to soothe her, she has said a few times something like 'I hate it when I do that' ie the abusive outburst.
I'm trying to get a measure of your DD. What are your DD's gifts? Despite her abusive behaviour she came home for what, a safe place, she see's you as safe, she trusts you?
I appreciate it's been a long, long haul for you and I get you she's not ready for change won't stick to anything and as you know well we can only change what's in our control, that can sometimes effect changes in others if and when they are ready.
WDx