I just want to share from a non-addict standpoint.
Growing up my father always warned my sister and I... "Dont make bad choices. If you do things that get you in trouble, get you in jail, your mom and I will not get you out because ONLY YOU are responsible for you. We will support you only in the right choices."
I knew he was serious so I lived my life abiding to those words. Surely, when my sister got into trouble with the law, he did not help her because she made the bad choices herself. Yet, when I chose to study hard, do well in school, go to college and continue higher education, they always supported me. I always knew that if I f-up... then I'd be the one cleaning up my own mess. Knowing that, I never wanted to f-up.
Support your son in the right choices only. He will not learn the lesson as long as you cushion his fall, which cuts short the lessons he was supposed to learn.
hang in there. :ghug3