Calling all want to be therapists

I’ve been dating a guy who is 3 years older than my father (I’m 18 now).As a little boy I was raped I can’t talk about this with my friends or family and I am cautious about discussing it with my therapist,So I met this guy when I was 16 and we are still dating! He was willing to wait until I became of legal age before having sex. So, he’s kind of a keeper (not just some perv for little boys) Now that I’m 18 he’s pressing for sex I never told him about being abused ( cause I don’t want to chase him away) so he doesn’t have any idea why I’m so reluctant about sex. I also told him I was a virgin which obviously I’m not I thought I was going to be okay with sex but we went farther than just kissing last time and I freaked out hard I thought I kept my composure but he noticed something was up I’m super concerned I’m going to lose him if I don’t have sex with him But if i become a basket case I think I’ll lose him too Any advice or comments are welcome But if you don’t understand the dynamics around older younger relationships or if you are against them please don’t respond.