In my opinion, you came on way too strong. I'm not trying to undermine your feelings, but the declarations of undying love and self-change might have been a little much. But, what's done is done.
This girl wants her space, and you need to give it to her. You've just dropped a bomb on her, and she'll need some time to sort through it, as the others have said. Meantime, you've got work to do.
For starters, get yourself clean. This is a girl who is in college and attending safe sex seminars. Clearly, her future matters to her. If you want her, you're gonna need to step up and be a man. Buy yourself a detox kit, and get on the job hunt. Make something of yourself.
Beyond that, you need to be prepared for the very real possibility that she may not be interested in a relationship with you. Make sure she knows that no matter what, you're still her friend.
Also, just a personal tidbit, lay off the name calling and kick the drama. You gonna tell me you never give it a tug? C'mon now. You need to grow up a bit. Try supporting her and treating her well. That's what manhood is about: supporting, protecting, and providing for those you love.