Sudden hesitation with bf

I was molested when I was younger, but I’ve gotten to a somewhat manageable point. Or at least I thought I had. I started having sex for the first time about a year ago, but suddenly I’m having hesitation. The best way I can think to describe it is a mini panic attack when my boyfriend tries to initiate any intimate contact. Why would this be happening so long after trauma and after having sex? It breaks my heart, he doesn’t understand why I’m suddenly not comfortable with him, and I don’t either.

Can someone help?