Me (23m) gf (21f) lied to me about someone she used to hook up with what do I do?

Me (23m) my gf (21f) my girlfriend lied to me about a previous person she used to hook up with what should I do?

My girlfriend lied to me about someone she used to hook up with. He tried to call her one night (about 2 months into the relationship) and she answered, he asked her to come over and smoke her answer was no I’m going to bed, no mention of I’m w my bf or anything like that eventually she got some weed and I asked her who she got it from and it happened to be this guy, she said all that happen was he pulled up and sold it to her through the window and then left this was after I asked her if she has had a past with him (she said no not at all but then I kept asking her and she admitted they were flirty together)

So she lied to me once nothing huge but I knew it was more than that. Now come to find out she’s hooked up with him multiple times before we started dating and he’s even gotten her a plan b. Now she’s back home out of state for summer(she’s in college) and I don’t know if I should wait to talk to her or if I should talk to her now? It just makes me super paranoid that she’s doing things she shouldn’t back at home and when I ask her things that she does i automatically think she’s lying with certain things because of that. What should I do? If I do talk to her about it rn what should I say and how should I go about it?

TL;DR my girlfriend has lied to me about a past person she hooked up with what should I do? (Please read)