I support what is written above as far as getting support from anon or other family of user groups. Visit the thread Murray posted to find support.
This is not your fault. I know you will hear / read this a lot, and I know it won't make you feel better. I need to stress how how many parents go through what you are going through. I write that NOT to diminish your situation at all, just to let you know you are not alone.
Your son needs to want to get better. You can not make him.
Good luck and keep us posted.