Okay, I fear I'm really going to get blasted here, but I hope not.
Are you kidding?
You haven't done anything wrong. A guy says he's divorcing his bat-shit crazy wife, you get to know each other, something of a relationship develops, it's off-again on-again, you discourage him from taking any steps on your behalf.......
Sounds to me like his wife is crazy, he can't control the situation or his life, and he reaches out to drag you into it.
I think it will be very, very hard, but there's no question you need to get away from it. (of course, I haven't read any posts but the OP, so my opinion is subject to change without notice.)