Weird trauma response

Whenever I'm talking to someone new or thinking of dating or even just being friends with a guy, for some reason I become very untrusting of them. My last crush that I had is an example, he was very chill and easygoing, didn't give me a reason to distrust him. For some reason though I had a nightmare that he was mad at me and cussed me out. My brain also imagined scenarios out of nowhere of him hurting me physically( these scenarios have happend with people who are my friend as well but it happens more with crushes or people who are close friends).. Just when I think the feeling goes away it comes back everytime.. It's very strange. I mean I don't have a nice history with men but i don't have anything against them. But for some reason even a guy being mad next to me (even when he's not mad at me) causes me to shut down and just make myself small so I don't cause any trouble or annoyance or be in their way