I've treated my two year old unfairly as well ( to put it lightly) and I understand the awful guilt that comes with it. I only didn't hurt myself because that would make me feel better and I didn't deserve to feel better. I didn't know how to punish myself and my anger was a driving force to getting help. So don't spend too much time obsessing on what happened. You cannot change the past. I understand how horrible you probably feel. It took me days to even look in the mirror and not hate myself.