I jumped in late, but wanted to address "something else other than addiction." There most likely is. First of all, there is a genetic component to addiction, but people self-medicate for a reason, often mental illness. My daughter has, I suspect a mood disorder. It's not so severe that she couldn't quit drugs and can't function, but it seems to pop up when she's under stress--she really freaks out and I have to calm her down. She won't see a therapist and is afraid to take medications both because she was once an addict and because the medications she tried made her feel much worse. She is getting closer to accepting therapy again, but it will take time. Which brings us to the question of, do we keep giving them chances even if they are mentally ill? My short answer is NO! Why? Because they are adults and we can't help them. It's completely up to them to get help and in my opinion they won't get that help if we baby them. Part of being an adult is admitting you are sick and getting the appropriate care, even if it's a mental illness. Not to mention that you absolutely can't get better if you use drugs. So I understand why you did what you did, but in my opinion it's over. He is well old enough to make the decision to take any help offered and to live his life as an adult. Unless he has a psychosis, and he doesn't, he knows how to behave and can take control of getting treatment for himself, in a dual-diagnosis facility. He has proven he is not willing.
You did the right thing. (((Hugs)))