Sometimes doing something stupid serves as a painful reminder of why we won't do something stupid again. I've done some things that I'm not proud of, and memories of those things remind me that I really don't want to go back there.

If you can rectify the situation do so. If you can't at least learn from your mistake so you won't repeat it. At least you have a conscience to know it was wrong, and that's a good thing. Once you learned your lesson don't keep holding it over your head. Just be more aware if that opportunity pops up again and make better choices. Beating youself up over it won't help because you simply relive the experience and don't learn from it. Admit your mistakes, resolve to do better and move on. I do hope you can recover from this and get yourself back ontrack soon.