I can definitely relate to your dilemma! I have been self medicating for years and when I didn't drink as often I began to use amphetamines. They seriously controlled my life and I was powerless to stop them. I didn't want to give them up even though I knew I couldn't stop using them if I tried. I never made the decision to quit, I was forced unwillingly. Honestly the first two months kick my butt. I got depressed and was tired al the time. It really sucked, Im not gonna lie.
Even though I was miserable for a while, sooner than I expected things started feeling better. I never want to go back on them because I know how addictive they are to me. My moods evened out and my mental health (and physical too) improved. If you were to place it in front of me today, I honestly can't say if I would be able to resist or not. I just had to rid myself of the temptation in my environment. I also started going to AA and thats helping me figure out how to cope without self medicating.
So my suggestion would be to talk to a professional about it if you can't quit on your own. Get it out of your reach. Try AA or dual diagnosis anonymous. Its really difficult to give it up and you might not be able to do it on your own. I just want you to know that I have been where you are, and from this side, things are so much better, it is worth it!