Sex advice help!!!

Girls I really need some help!!

I’m a virgin (barely done anything with a guy because of a sexual assault when I was younger) (I’m 23) and I’ve met an amazing man, we’ve been together just over 3 months now. We’re both really open with each other but the one thing I haven’t told him is that I’m a virgin and why.

Several things I need help with;

1: how do I tell him/should I tell him the reason why? (I’ve told people in the past and they either haven’t believed me/ignored me)

2: because I’m so inexperienced, how can I make sure that the sex in general doesn’t suck? (I know his favourite position is missionary) tips and tricks to help would really be great😭

Thanks girls!!!!