I need advice about sex and whatnot.

I'm nineteen, and there's this guy I like. He likes me too. And I am so ready for sex (this would be my first time), but I haven't told him I was sexually abused by my father and I still suffer PTSD from it. I'm worried that I might have a panic attack or something while it's going on. I don't really want to tell him in case it's kind of a turn off, but I also feel like I should. Any advice?