lms1, please don't feel bad. All of us have done too much trying to save our children. It is a learning process. I like the saying, "I did the best I could with what I knew at the time."
Until your son is willing to break with the drug using friends, he will not get clean. That is what they always tell you to look for in rehab. A complete break with the previous drug using friends is necessary to stay sober.
I hope this is the time that your son chooses sobriety. All you can do is be there to cheer him on if and when he is serious about recovery.
~Kathy