The effects of abuse aren't easy to get rid of. How many people are determined not to be like their mother or father, but find themselves reacting to some situations the same way? Don't beat yourself up. Take note of these times, and learn from them. Then you can change them. You're not a bad person because you make mistakes. I know you're not a bad person because you didn't mean to hurt your son and because you regret it. Parenting isn't easy, even for those who didn't come from abusive homes. Sometimes parents make mistakes, even bad ones, but it doesn't mean your kid will be scarred for life.

I think it's ok to say something like, "My dad was sometimes very mean to me, and it hurt my feelings and made me very scared, and that sometimes still affects me today. You also know my OCD sometimes stresses me out. I'm sorry I let my anger get out of control, but I promise you, I love you more than anyone, and I'm going to do my best not to do that again." If you find yourself feeling angry like that again, you might have him tell you you're not being rational, and maybe that will help you realize you're letting your anger get the best of you. But you have to be sure you won't get further angered if he does that; if you think that will be a problem, don't have him say that. But try to get yourself under control enough to say, "I need to go into another room and calm down. Then we can discuss this situation rationally."

Like LMo says, forgive yourself. You're a good person. Even good parents have flaws.