School reunion

Last year I went to a school reunion and met up with 4 girls I hadn't seen since leaving. We had a good time and kept in touch, agreeing to meet up again at some point. Another girl has now joined the group. She and I were very close from the age of 7 (besties!!) then around the age of 13 she dumped me in a particularly cruel way. She joined up with another girl in our class and started doing things with her that we would normally have done. One day they went swimming and she rang my home. My mom told me who was on the phone but when I spoke it was this other girl. I said hi to her but then the first girl came back on and denied the other girl was there. They kept switching the phone but my friend kept saying the other girls wasn't there. They carried out doing things together and excluding me so eventually I drifted off and became friends with other people at school. This episode really hurt and affected me but I had put it out of my mind - it was over 30 years ago. Now this girl is back in our group, planning to come to the next reunion. Everyone else remembers her as the great gymnast and sporting person but I can't see past what she did. I keep our group chats friendly and neutral but I don't want to see her again but I also don't want to miss out on meeting the other girls whose company I enjoy. I know I probably need to grow up and quite honestly am shocked at what this has stirred up inside me. I thought it was long gone. Advice please

Good point. I think I felt betrayed. And there have been incidents in more recent life that I have overreacted when I have felt let down. My husband has a family from his first marriage who quite often play the "we want Mom and Dad together" card at family weddings etc and I am just ignored. This kind of thing puts me into over drive. Probably all the same thing really isn't it