Flashback problems

A couple years ago, I was raped and sometimes have flashbacks to the night it happened. The other night, my boyfriend was having sex with me and in the middle I started having flashbacks and began crying and told him to stop. He now can’t get the image of me crying out of his mind and I don’t know how to help him. He is uncomfortable with having sex with me now, but i’ve told him repeatedly it wasn’t him nor was it his fault that this happened. I don’t know what to do.