So I think I just became a cuckold in my relationship. Some background below.

I opened up my relationship with my girlfriend recently. I wanted to keep the status of our new open relationship a secret, but she ended up telling one of her be friend who essentially told everyone in our circle of friends. Fast forward a couple months ago, we go to a party. It was mostly dudes aside from my girlfriend and another girl I had a crush on. Throughout the party I thought the vibe was a little weird, it felt like my girlfriend was getting a lot of attention. Lots of guys were trying to talk to her and a lot of people were looking over at her. But down the line, close to midnight, things started going well with us. It actually got to the point where I was making out with my crush, but at the same time my girlfriend also had a guy all over her… and she was doing a LOT OF PDA (making out in public, getting felt up on the couch). More PDA than she has ever done with me (she’s really not into showing affection in public… at least not with me. Towards the end of the night I sorta struck out, my date ended up leaving and my girlfriend got a bit more lucky with some of my friends. That’s all I want to share here publicly, I can go into the details once we start chatting. I prefer Reddit chat over PM.

Did I make a mistake? Should I not bring my girlfriend to a party full of guys? Once I struck out, would it have been fair to ask my girlfriend that she needs to stop what she’s doing with the other guy and go home with me? I’m not quite understanding the situation and how I feel, I think a woman’s perspective would be very helpful in navigating all this. It would be a big plus if you have experience in these types of situations/relationships.