Colleen; it sounds like you are where I was at a few months ago. I would let him finish his classes since it's so close and then give him an ultimatum of move out OR go to rehab. I knew my son would have to go to a shelter if he "moved out" but I did not know how else to stop the madness and I was desperate. It worked for us because he did go to rehab. And even though he said he was only going because we "made him" I did not care. He needed help and we knew it and we needed a break. We knew we had to follow through and I was terrified because he was the kid that never even wanted to spend the night at someone else's house. He always wanted to be home, in his own bed.
I finally realized I couldn't fix it and I couldn't go on like that anymore; with all of that in my home.
You have to do what you feel is best but I hate to see your posts and how much you are suffering. I know that pain and it's horrible and no way to live - for him either.