I lied to my girlfriend and now I'm freaking out

Me and my girlfriend have been together for a while and she's been wanting to have sex, but I may have told a little white lie... I'm 27 and still a virgin.... Well technically. In high school I dealt with a sexual assault from my teacher but I don't count that. Because of what happened in High school it just turned me off from sex for a while. I tried to get into porn and masturbating but honestly anything sexual just freaked me out. I became extremely scared of sexuality. After YEARS if therapy I'm finally in a better mind set about sex and even masturbate every so often. But I still never lost my virginity. It just didn't happen. But who the hell says they're almost a 30 year old virgin. Especially a guy. So I kind of lied.... Well I guess not exactly lied, but never told her, which in a way is lying. Anyway she doesn't know I'm a virgin and she wants to have sex. I'm scared if I tell her she will think I'm immature or something...