Should I feel guilty when I kick my boyfriend in the crotch?

I don't know why, but I think it's funny. Last year my ex was saying crap in front of everyone at school about me and I kicked him so hard in the crotch he fell down. I regret it, but I felt good for myself. I don't know why I do it, but sometimes it's right to do. Some of my boyfriends try to grope me and I don't like it. I kick them when they do that. Sometimes I just do it not even aware of what I'm doing. please help me.