I have not officially terminated contact with my AD, but by refusing to help her find treatment (she walked out of treament 8 times before and never finished treament), by not giving her $, not rescuing her from abusinve BF anymore(she goes right back to him), not taking her to HIV clinic appts (she is verbally abusive when I do even though she asks me to take her), not letting her come home unless clean for 30 days (never stayed clean that long), -Well, it turns out she has very little use for me now that I have set some boundaries. She rarely calls now and rarely answers her phone when I call her. I didn't have to cut contact; it sort of happened on its own when I refused to be used and abused.
Either way, its up to you what you are willing to do and not do. There really are no rules when it comes to this stuff. As moms, so much of what is good for us is also painful for us. But the pain (as you know) is there anyway, and 'trying to help' is often the most painful of all.