I agree with what everyone has posted.
Seek AlAnon for yourself and lead by example. If you are growing and learning about yourself, taking pride in yourself, having strong personal boundaries, etc. that will shine through to your son.
Don't let him rule your home or your relationship, be loving but firm in what you expect of him. Our kids, no matter what age, need structure and boundaries - it's easier at times not to enforce, but so much better in the long run if you do.
Both my kids (now grown) wanted nothing to do with counseling after Dad & I divorced. I wonder now if I had stuck with it, would it have been better? Would AS not have gotten into drugs? Would my daughter not be sooo high strung and dealing w/mental health issues? I'll never know, but have wondered.
Good luck, keep doing the next right thing, that's all we can do!