Ok should i trust him?

So I just started dating this guy today. I met him through a friend when we were all hanging out. We got drunk and i made out with them both (im bisexual) but once the buzz wore off for me (they were both drunk) i was getting jealous and i realized i actually had feelings for him. So when we got to the house he would make out with me then her again and again. But then he stopped doing it with me and i left the room. They started to have sex but my friend kept saying no i cant hurt her she likes you alot (very thin walls) so he comes out and gets me and we all go back to snuggling. she falls asleep and we start to makeout and he asked me out i said yes. The next day he was snuggling with her more but not kissing her (like he was me) and she tried to kiss him and he wouldnt let her. I really am confused