My exh is not an addict of any kind that I know of, but he was abusive, mostly mentally, occasionally physically. (My qualifier is my new H). Everything was documented, the kids had a guardian, and my ex still got 50/50 because nothing was ever directed AT the kids.
The bright side is, 18 mo after the divorce he decided he didn't want the hassle of being a dad anymore (he never did really). He moved to Mexico, I went back to court and got sole legal and physical. Sometimes it just works out after a while. Most of the time they are just angry over the divorce and want to get back at you.
My AH also has a daughter from his first marriage, he and her mother divorced when she was seven, he got every other weekend, but he didn't always stick to it because of his drinking. She is 23 now and has very little contact with him, even though she has his first grandchild now.
They make their bed and many times, IMHO the kids themselves make them lay in them.True for my AH and my exh.