These are hard awkward moments that will now be a part of your life. Next time, try to imagine how you'll handle the event before hand so that you won't be anxious. It used to be difficult for me and my ex-husband (and our spouses) to be at the kids events together, but now that we simply don't speak or make eye contact with each other (not because that would be my first choice) people would never even know that he and I were once married...
Of course it hurts. You know you're a better person, but it hurts to see people act like that and it hurts to have people do things that can deliberately hurt others, especially right in front of their noses. That's what happened here and that's why it hurts. They're the ones that are the saddest though, because they're the ones acting the way they are. Hugs for you and keep looking at and feeding off of the things that are good and don't hurt...that's where the real love is.
I can definitely see why you are hurting. I wish I could just give you a great big hug! AJ