Losing my virginity

I know for a fact I'm ready to have sex. There's no way around it. My boyfriend and I have talked about it and we're both ready. The thing is I've been taken advantage of in the past and have been made to do things I want comfortable with. Whenever it comes to the point where something could happen between us, I shut down. Bad memories come up. I have talked to him about it and he is super understanding and caring. It's not that I don't want to be with him, because I want to take this next step in our relationship. How do I push those memories away? I'm not saying I want to repress them or anything, but it's a moment that should be shared between the two of us, not the assholes from my past.