I would just leave. I'd email/call my parents and tell them that they were right...I'd see if I can find someone to help me get home and maybe a girlfriend to stay with. There are women shelters that you can go to in a pinch that don't cost anything, some will help you find a job. There are more options then the one of staying.

I say he's already cheating in his heart and that he's resentful for you to be there which only surfaces when he's high. This is abuse that you don't need.

And quit spending money on him! Tell him your broke and that he needs to start paying his own way like a real man would.

Cut your losses and get out of there hun.