I went through very similar things with my son. I finally had to insist we have lots of space between us. I insisted he move and become independent. It was harsh and worrisome at the time, and now he is doing much better and values things he has to work hard for. We always had a good relationship at the core, like you and AJ do, and that came shining through when the opportunity to make me his target of rage was taken away; we have a nice adult loving relationship now. He still has trouble dealing with things sometimes and used to call me to rage; it took a few calls where I had to say calmly and firmly that he couldn't do that anymore, that his threats to harm himself were abusive to me and that if he felt that way he needed to go to the ER. A few times I had to disconnect when he would continue. But eventually, when he understood that we can talk about anything, but I won't accept his rage anymore, in any form, we got to where we both wanted to be. And more life experiences like working and more social contact helped him. He has received mental health help since he was a teen, and he continues that.

I really admire you for knowing the kind of relationship you want with AJ, and letting him know what's acceptable to you and what isn't. It is a hard thing to do, especially when it is a relationship that has been going in one direction for a while, and you want to change that direction.