Ask yourself - is it worth arguing over? Make your feels known and ask to be invited next time, then accept it and move on. No use arguing and dragging it out, that will just hurt both of you even more.
I’m sure there was no intention to hurt you, those who invited him probably just wanted a boys trip, he may not have realised it was this important to you.
Also it is important for guys to hang out without their partners there, and same for girls to hang out without any guys around.
I think it’s understandable that you’re hurt, but don’t see either one of you as right or wrong personally.
It’s not how you feel that determines if someone’s in the wrong, but how the person that’s feeling them reacts to those emotions.
That’s my view on it anyway. :)