Be his sounding board, be sincere, be honest, and then let him do what he is gonna do. Too bad you cannot save someone from himself and right now he is his own WORST enemy. It sounds like he is suffering from a brokenheart, and turning to something like Heroin is not the wisest thing to do, but he won't see that for some time. Prepare yourself..its gonna get HOrrible b4 it gets any better. Good luck wit dat!