The best thing to to would be to get him into a 12-Step program like NARANON. You could attend the support group associated with the program. They'll tell you not to let the addict's illness make you sick. "Let go and let God" is their byword. You'll hear plenty of stories from parents, sibs, friends of addicts who've gone through far more than you have--and who have plenty of their wisdom to share with you.