Don't know (20F) to to accept my partner's (22M) past sex life

Hello everyone!

Me and my partner are in our first relationships, by my bf had 2 sexual intercourses before we met: one with his ex classmate and one in a threesome - he was invited by a couple he barely knew. And I can't accept it. We've talked about it and he said, that it was just sex, he wanted to gain some experience, etc. But he also stated that he didn't like any of that. So for me it feels like he couldn't say "no" (in both cases he did not initiate sex) and it worries me. I'm crying, talk to physiotherapist, we've discussed it with my bf, but i can't understand it.

I can't understand, why he didn't stop DURING the process, when he realised perfectly well, that it's bullshit. I don't want to ruin our relationships with jealousy but I don't know what to do about it, it's really weird and disgusting to me.

How did you deal with it, guys?