Hi Jules
I an a new member. We don't know each other. I echo absolutely somewhereoutthere about the possibility of a new IEP, and getting school to take on some of the school-related responsibilities so that home can be less stressful. Also, what about after school care? This would be better for him, I think, because the influence of peers pulls for better behavior.
Try to pick your battles, and minimize the rest, don't you think? Cut his hair, short, for example (around here where I live, bald is in....). Withhold things he likes until he showers, brushes his teeth. Abusive? Sorry.
People have blamed me because I picked my battles with my son. Things have not turned out well. But this is about your survival, too. If you or your marriage don't make it...what happens then?
We are not there with you, but somewhereoutthere called it right. You need proper diagnoses. With a diagnosis you may be able to get more support, possibly even Regional Center. Please understand, it is easy to give advice, and please ignore what is off target. My heart is with you.