This is so difficult, and something I can relate to. I think the first step is respecting yourself and not letting their behaviours become your own problem, then secondly, being dead honest...even if that means they push you away. I think that is the most respectful thing to do.
I don't know your situation, but with legality being involved it sounds very serious. I have had to involve police due to the behaviour of a family member, my brother, and recently there have been some issues with him hoarding and potentially hindering the sale of an inherited property. I was honest with him about the implications, and that I would have to take legal action if he did hinder the sale. I explained that I had to do this for my own sanity, it would be better for us all in the long run, and that I was giving him fair warning. He doesn't respect my decisions, but I respect him enough to give him opportunities to do the right thing, and if he chooses to behave disrespectfully, and push me away, I can respect that is his choice. It's hard to process. Therapy helps me process these things. Talking about things on here helps too.