Hi Nate! Welcome to MaleSurvivor; sorry to see you here... ;-)
It's alright for you to say, "Let's take this at my pace," or "I'm not comfortable with this right now, let's do something else." at any time in any relationship. If he persists, you have to insist, and then you know what kind of guy he is. If he's a nice guy, he'll say something like "Oh, I'm sorry! I just got in a hurry cause I like you. We'll slow down." That guy will be a keeper, at least for awhile.
Meanwhile, don't use that as an excuse. Don't hide behind your abuse and withdraw. If he's really interested, you can tell him later. In the meantime, the fact that you're not easy might even be attractive to him.
Finally, get some help with those triggers. There are people here who can give you advice, coping mechanisms and lots of careing help. I'd also like to be the first to suggest that you find someone you trust to talk to about this face to face, preferably someone with some training or familiarity with CSA. At least a coach, mentor or clergyman that you trust. I think you'll find that you feel better.
Best of luck!
"That which does not kill us, surely makes us stonger." - Neitsche