Hey there OP,
Props to you for making attempts to help your friend.
Judging from your friend's situation, he is more than waist-deep into his drug addiction. Of course, the only way for him to get better is to go cold-turkey and rehab. Since it's an addiction to chemical compounds, he's gonna have go through hell to break the nasty habit.
You sound really frustrated, as a caring friend most likely will be like. But in my opinion, I may not know what his family is like...BUT I think it's your friend's "MOTHER" that should be first to take some action.
You mentioned that he lives with his mother. The mother can for example:
-threaten to kick him out of the house
-check him into rehab
-take complete control/ limit your friend's finances
Telling him to screw off isn't really necessary, but in all honesty, just being there for him when he needs it; is all you can really do for him.
Props again to you OP,
