Why do I keep doing things that go against my morals?

It only sets me up for a world of hurt. Is it because I need to experience humility? Because I have. On more than one occassion at this point. I'm now disappointed in myself, in others, hurt by said others, etc. I'm angry, frustrated, sad all because I did something I shouldn't have. Ugh. And I can't stop thinking about it either. And about the other person involved (actually, they are all I've thought about the past couple of days). I hate that. I'm trying not to regret what I did because regretting it doesn't change the fact that it happened. I just need to move on. I need to refocus and work towards achieving my goals. But it's easier said than done when you can't get your mind off of someone. Please don't let this hurt like it did the last time someone hurt me because I honestly can't take it. I know I probably won't survive it because I barely survived the last time. I have to move on. Hopefully I can.