Mind fucked

T

Soo me and my fwb have been talking to each other for about three months, we haven't did anything yet but he told me that he has had sex with 3 people when we first started talking but last night we were sharing stories and he had some very interesting stories so today I asked him how many people has he really had sex with and he says 12 🙃🙃....idk what to do because I mean I am pretty upset that he didn't tell me before because I really would've stopped talking to him earlier because I don't wanna take any chances of catching anything and I only had sex with 2 people....btw I'm 17 and he's 20