I thought it was a threesome but I might have gotten cucked [first time]

My girlfriend and I have been dating for a very long time and were the only people we’d ever done anything with. We took each other’s virginity and everything. Recently since being in college she’s been wanting to explore more and talked a lot about how she thought a threesome would be hot but only wanted to with another guy. After some convincing I agreed and I told her to find the guy. She found him and showed him to me and had been talking to him for a while. The night comes which was a few months ago and he’s a very large black guy. Hes gotta be 6 inches taller and 6 inches longer than me lol. I got so nervous and didn’t really know what to do….. She started going down on him while holding onto me and after I bit of this I don’t know what happened but I couldn’t hold it back anymore and I came before we all started having sex. He ended up fucking her for hours while I just kinda stood by… For a bit I ate her pussy and ass when she asked me to. But it was really all focused on them. I’d never seen her react to sex like that before. She came from sex for the first time and did over and over. It was a wild experience and she hasn’t really been able to stop since