Barbdee, I hear a lot of pain and bitterness in your post. I'm sorry this happened and I know how awful it is when our son's relapse. Something that helped me a lot was going to meetings and working a program that helped me keep my balance and let go of the fear.
Sadly or not, recovering addicts have to face life on life's terms and learn what situations they must simply avoid to keep themselves safe. Hopefully your son has learned from this and learned that it's not "those people" who made him relapse. It takes time and healing and if he came away from this a little wiser, then maybe it was a lesson that he just needed to learn.
My prayers go out for him, that he can get back on that good path again and stay there.
Hugs