Just found out something about my friends, any tips on how to handle it?

This isn’t necessarily a relationship as is dating, its a friend relationship. I was on call with one of my friends, Rina. We started talking about the group chat that we are in. She brought up how my best friend Addy and another friend Ray got together. I was shocked, I didnt believe her, I thought “that cant be true, shes my best friend, i would have known”. I asked Addys girlfriend, alin, one of my other best friends about it, and it was true. At the time they got together, Addy and Lin got avoidant in a way. I heard from them less. It wad like i was screaming into a void when talking to them. When we call, if one isnt there, they end up leaving me to call eachother. I feel so left out by them. One of our friends who they barely talk to knew before me. I didnt even know she was poly. They hid this for over a week. I was told that Addy was being avoidant because of her family issues. Another lie. I just dont know how to go with knowing this.