Is it just me?

As a child I was sexually abused for 7 years. Because of that I became very promiscuous at a young age and began having sex at 13 years old. During those years I didn't understand what happened to me as a child. It wasn't affecting my life, or at least in ways that I could notice.

At 14 I told my mom I was a lesbian and she didn't understand why. She was clueless and of course thought it was a phase. But throughout high school I only dated women. During that time, if I was intimate with someone, right before I felt like I would have an orgasm my body would tense up and I would start crying.

Senior year of high school I thought that if I had sex with another guy maybe I would break down. I slept with someone I barely even knew and I actually enjoyed myself. Until I started having sex with him on multiple occasions and then eventually I started to cry.

Now.. I've been dating a guy for a year now, and we often have sex. I tend to get very very horny and when we start everything is going great.. but right until I feel the urge like I have to "pee" I get tense. I start thinking of what happened. And I try to tell myself not to think about it and to just cum and enjoy myself. And I can never make it out of that. I try and I try to finish and I either get scared or I lose my sex drive and it no longer feels good. It starts to hurt. I hate myself because my boyfriend doesn't understand and I don't want him to think I'm not sexually pleased by him. I am.

Does anyone have any advice for me? Or can relate to me? Please help.