It is a pattern with some men. If they break it off with one nightmare, they'll hook up with another just as bad. (I've seen a family friend lose his life savings and his health chasing high maintenance nutcases). Has a lot to do with self esteem. OP I feel for you, watching your friend possibly wreck his life. You are right to take a stand, but it WILL cost you. Take care, and realize your friend may understand one day.