GM, It is better for the kids to have a bad parent than none at all.
It may be somewhat heartening to you to hear what happened w/my X. He was clueless w/then-baby D and I stopped enabling. I just left her with him and ignored anything that wasn't directly concerned with safety.
After 5+ years, X has finally begun to act more like a father to D. He is less resentful of spending time with her (he really treated her like a burden, much as he treated me. Now he seems to like spending time with her more, even though it's still minimal). Maybe their R improved because she doesn't have a "big sister" any more. Anyway, I understand about "worst enemy" situation because I got the spew, too, and was quite afraid of him. Ignore him as much as you can, and you're right--encourage the R but don't enable it.
X has been severely humbled by middle age. As we all have, in some ways. I have begun to realize that D is one of his few bright spots now.
I sometimes wonder if teenagers are somewhat threatening to MLCers. I mean, it's teens who are supposed to be rebellious. Not their middle-aged fathers. Probably makes the MLCers uncomfortable.
M: 16 years Bomb 4/07 OW 20s long gone Divorced 11/09 I remarried New Guy Cooperative r w/X regarding D