Still having flashbacks

I was in a relationship with a guy for almost 7 months and he finally agreed to spend the night with me. In the middle of the night I wake up to having my pants pulled down with little knowledge of what was going on. I had no idea what to do because I froze. It was like I was paralyzed the whole time. The memories have been coming back a lot recently and I honestly don't know how to make them go away. Its causing a few problems with my current boyfriend and I just want to get rid of that part of my life all together.