Cheated on, hurt yes but ok. Your take on it?

I know this is long, but its very interesting situation. Basically my boyfriend of 6 months recieved a blow job from a semi-friend of mine. Here’s what happened. I was at boyfriend house and he was throwing a party, the people there were T (female) C(female) my boyfriend, myself, N (male) and D (male). T and C are lesbians and are dating. D has a girlfriend but I think their both in the relationship for sx, and has had a girlfriend for over 2 years. So we’re drinking, C gets to drunk ends up in the bathroom puking, her girlfriend T can’t handle puke comes and gets me, I don’t mind and spend the next 2 hours with C in the bathroom. about an hour in my boyfriend knocks on the door and tell me he has to talk to me right away. I leave the bathroom and he sits me on his bed, tears in his eyes (from a guy who doesn’t remember the last time he cried) and tell me that T gave him a bj outside. (Everyone goes outback a lot to smoke). Im calm about it and tell him its ok (lots of detail I won’t go into it unless someone wants me to lol). So he tells me the full story. T, whos and alcoholic, and drunk at the time, and and my boyfriend are outside smoking. and has a huge scar on his penis from a braces and bj accident (Ouch I know) and T wants to c it. So, and not caring, shows it to her, she suddenly starts yanking on it and jacking him off…some how my boyfriend gets involved, then D comes out in his boxers (no big deal at my bfs parties) and she reaches in and starts going at him. She ends up blowing all three, then sex gets brought up, so they go to go behind the shed and my boyfriend snaps out of it, at which point he comes in to tell me. The other 2, we know for a fact had sex with her. So basically, in hurt, but im very proud that he stopped it at that point and didn’t go any further (if it did id dump his a*). Neither and or D or T are going to tell their partners (tho I want to for them but its not my place to tell) but my boyfriend told me right away. So I don’t know, its been a few days, had our 6 month celebration today. I love him so much and hes wonderful to me, except for this. What makes this all worse was while this went on, I was inside the house taking care of that wore’s beautiful, caring girlfriend. so it wasn’t like my boyfriend was around all the sexy influence and didn’t have someone to satisfy him…I was RIGHT THERE. So I don’t know…Im confused, and really don’t have anyone to talk about it with (I talk about everything to my boyfriend) so… for those who read this thanks and you have any suggestions or opinions or relating stories it would be muchly appreciated.
P.S my boyfriend was also high along with being drunk. (and sexually teased and pent up all day)