I don't think you are over-reacting either, it's rather your former experience helping you survive. But, I also think that your new husband seems from what you tell here to be honest and not really violent(I'm not sure whether your text makes your husband seem like an ok guy because you want to believe he is or because he really is

). I have been hitting my fist in a wall in frustration once myself, but I don't think I could even hit someone in self defense. It is scary though, in the prison I worked I experienced several times that prisoners suddenly hit their fist in the wall or on the table when they told me about something frustrating. They would always say sorry afterwards and explain that they were not going to hit me, but that they needed to get out some of the energy the frustration gave them. I never thought they were going to hit me, but the sudden movement of violence is startling.
Did you talk to your husband about how you felt the hit from your past? I think it is very important that your husband learns to control that type of reactions, espescially considering the background you have. Maybe you should have a time out where he can lock himself into the bathroom and yell as loud as he can? Sometimes that is a good way of getting out some anger.
Good luck.
Charlie