Anxietygirl, my reply will probably be quite unpopular... but I just want to express my point of view of your situation.
When I was reading your post I couldn't help but identify with your son. Probably because we're around the same age (I'm 20), but also because a lot of his behaviours and issues sounded so familiar to me. Of course, I don't know him, but from what you said it appears as clear as day that he's suffering. He attempted suicide 3 times... well, to do that one must be pretty much in agony (I know what I'm talking about). And he's still talking about it, so he's still struggling.
About the drug abuse, I doubt he developed an addiction because he was constantly looking for fun. I think what he wanted from the pills was relief. When the pain you feel inside becomes unbearable, you would do anything to make it go away. If nothing else works you eventually resort to alcohol or drugs (Again, I know what that's like too).
He doesn't want to go to counseling. I don't know if he tried that already... If he did and it didn't help, he probably thinks it's useless; or worse, he thinks nothing can help him any more. (Been there too). If he didn't, there are lots of reasonable explanations why he doesn't feel like trying.
About the fact that he's abusive I won't say anything, because that's obviously wrong. But he's having a hard time and guys that age often express their pain through aggressiveness. It doesn't mean he hates you or he likes to be mean to you or anybody else. He just doesn't realize he's hurting you, simply because he never thought about it.

I hope this doesn't sound judgemental or too apologetic of your son's unacceptable behaviors. I don't mean to question the properness of your feelings or to judge you in any way. I just wanted to present things from a different perspective.
After I read your post I suddenly thought: "Wow, if this is the way my parents see me, that explains a lot". See, I don't work or study either... and I'm well aware this may lead to the conclusion that I'm lazy and spoiled. But the truth is, I'd really like to do something with my life, I want it so badly... I just can't because of my problems. And your son is clearly suffering very much too, which might limit him more than it seems.
This is just my opinion... and I apologize if I'm out of line.
I wish you the best of luck