That is devastating for those you describe in the initial post! I cannot even imagine it coming to that -- that is, doing over and over what one thinks are acts of kindness, compassion, and meaning well when trying to "help" an addict through tough times and then ending up themselves in dire straits.
I was given a heads up years back (via this site and forums and support) and I guess you could say "re-trained" myself into thinking I should detach (not easy but can be done) and not continue to enable one who attempted to manipulate family members into taking care of his business so he could continue with his chaotic lifestyle. I do love myself and the addict enough to know now to resist the temptation to try to fix things for him.
Being entirely honest with oneself is a good exercise. Sigmund Freud