Idk why! Please help!!!

So I have been talking to this guy, and we started dating the 16th. But I haven't been in a relationship in two years cause when I used to I just got hurt, so I focused on my daughter and myself.

I really like him and super happy, but I'm terrified that I'll get hurt again, they way I am I try to hurt them before they hurt me. He keeps telling me "he won't hurt me" but I just don't want to get hurt. I'm pulling away from him, not meaning to but I am. I have no idea what the hell to do. He really does make me happy, I haven't felt this way in a long time. But Idk what's wrong with me.