Dear BF,
I'm so sorry for your troubles. The folks here have given you so much excellent advice (legal aid, adult protective services, etc...) and I'm glad you're acting on it.
I don't think you're BIL has a legal leg to stand on and that things will work out on your favour. However, I hate to see you being put through so much unnecessary grief and stress. The thought of you awake all night with worry makes me sad - and angry.
I'm with the others who think your BIL should be captain of the Olympic evil clod team. I'd love to give him a sizeable chunk of what's left of my mind. Frankly, there's a special area of the "warm place" reserved for people like him.
Hang in there - things are going to work out.