SERIOUSLY! Help me the fuck out!

There's a close friend of mine who got mixed in with the wrong people, he got into gangs, drugs and all sorts of fucked up shit. After about a year he was getting better, he was able to stay sober for a long time. But recently, he got arrested, he went back to dealing and doing drugs. First it was weed, now its cocaine. He was found with 2 oz of it, and a 0.25 revolver in his possession. He swore he was going straight. And he then started cheating on his girlfriend. Me and him have been like brothers for 6 years. I can't just leave him. I can help him, but I'm just stuck. I'm lost in this forest, this labyrinth of confusion, questions, and fear. I just don't know how to help him. He is a better person than what he is now. I know its inside him. I just don't know how to free the trapped, good person, one who would rather lose a hand than touch drugs or alcohol, one who will back up those he cares for in any situation. I just can't figure out how to set the real him that's inside free. And from what I heard, he's been a coke addict since he was 10... I just don't want to believe it. But.... I'm not to sure what to think anymore... Was I wrong about him? Was I just too blind to see the dreaded truth? Was I just waltzing down the beautiful road of lies and deceit, and didn't wish to go through the horrifying p, dreadful narrow walkway of truth? I've been fed lies for my whole life, and I just eat them up as though they were candy. I guess its true, that sometimes its better to tell a white lie, then to reveal the a horrible truth. And the things we don't know, really won't hurt us....

So I ask you, my Hazardous brothers and sisters, I ask for your aid in this matter, I ask for clarification, answers, advice, and overall wisdom. What should I do? How can I deal with this? I used to think I could handle any of my problems on my own, like I always had to... But now, shit gets real...