I experience something similar, only it's with my alcoholic brother, who has lived with us for about five years.
My brother is no longer willing to try to quit drinking, and has told us that point-blank.
Every so often we'll have a confrontation, usually over him not being able to pay his share of the expenses here, but always having plenty of money for beer and cigarettes.
When I confront him, I tell him he has to move, but then it blows over, and things continue on as they always do.
We're going through this right now. I told him just last week that our lifestyles aren't a good match any more, and he needs to find his own place.
I wish things could be different. I wish I didn't have to send him away from our home, but I don't know what else to do. Once my anger has calmed down, I start to think that things weren't so bad, but the stress of the way he lives that effects me is overwhelming sometimes.