I don't know what issues your son has, but I have found help at AlAnon for families. I go tonight for a meeting. It's not just for people who loves someone with an addiction... Some times the addiction is ours...in that we can't stop our behavior. I get so enmeshed in my child's problem, that I have problems.
There is a book called CoDependent No More that is helpful. You probably know all these things, but so hard to live it.
There is a wonderful post in the Parent Emeritus forum about detachment. It's always one of the first four posts. It has a lot of good information.
Keep coming back to this site...it helps to talk to others who know what you are going thru. Ksm