I totally agree with JWK’s post. Focusing on the positives, being very calm and matter of fact about messes “I see you’ve smeared poo on the wall. In our house, we use the bathroom. Here’s a cloth to clean it up. If you need more supplies to clean, let me know.” Calmly walk away. Repeat as necessary.
I know when my son is at his worst, what I want to do is wring his neck and my yelling reaches a peak by the end of the week. But what he actually NEEDS is real connection time and for me to back off of the discipline. I have to switch up our activities to set him up to succeed (ie: he is running laps smashing things in the morning after breakfast, so instead of being indoors we go for a bike ride to eliminate the opportunity for misbehaviour). I have to clench my jaw to hold in the frustration and anger as he tries to push my buttons and go back into the fray of things, but if I can hold out for a couple days and do what JWK suggests, by the end of the week I have my kid back.
I don’t have ADHD or ODD, but I would have been described very much how your therapist has described your daughter. You are the one she can trust, so she lashes out at you the most to try and make you leave too. That kid was me. My parents were awful so I would act out to them, but also even more to the couple of adults in my school life who truly cared. (I knew they couldn’t/wouldn’t hit me or hurt me, so it was safe to be super awful with them). Pushing those people away confirms your fears that they’re going to leave anyways, and it’s easier to get that over with than keep on waiting and hoping they don’t leave you. I tell you this because what I needed was calmness, continued kindness and reassurance in spite of my behaviour. The ones who did this for me, despite my shitty attitude and nasty behaviour, became life-long mentors for me and helped me survive into adulthood. Try not to take it personally- it really isn’t about you, it’s about her deep-seated fears and previous experiences. You might just be that one person she really needs right now, if you can see past her behaviour to the very small, wounded girl in there.
I don’t know how old your other kids are, but if they are old enough I’d have a chat with them explaining that she’s really struggling right now with some big feelings, but she is a very important part of your family and you are all going to be there and help her through it. You might explain that sometimes it may seem she’s being rewarded for bad behaviour, but you are actually focusing on good behaviour because it helps her feel better about herself and want to try harder. Or something more age-appropriate.
Is there a hobby or talent she’s interested in or good at, that maybe she could participate in over the summer to give you a break? Or a Big Brothers Big Sisters program in your area that might provide a mentor?