Your friend sounds like my Father and Brother... to a degree, the selfishness of an addict is unbelievable...me me me is so true.
I watched my Father get locked up for months as well as put under a year of house arrest, he would disappear for days all through my highschool years, (I only lived with him from 13-17) During that time I am amazed at the attitude he had concerning his rights to do what he wanted. If somebady in the house didn't like, "they could get the f' out!" His way of dealing with things was to give his girlfriend and me and my friends drugs and alcohol also...
This is after years of trying to get over his heroin addictions and being in prison for that as well...
Now I watch my brother through the years do the same kind of junk!!! Drinking, drugs. Blaming everyone else... when his girlfriend tries to leave him he just says oh well, what can I do, she is so angry and I don't get it. Looks like she is taking the kids and going... No sadness no trying for the kids. Of course he takes her back, with no promise of change...
I haven't talked to either one in a long time because they are so selfish and only think of themselves...
It is always rehab and then well I can have a drink, or two or six... I have heard from my brother that my father is back to doing drugs as well as drinking again.
I hope your friend learns and finds a good path for herself...
I think it is too late for my father and I...
Maybe her children have a chance with their Mommy.