Am I wrong to be angry?!

My boyfriend left for boot camp in June. We both knew it was going to be hard but at least we had letters to count on. He never gave me his address. I went a month with out know what the fuck was going on and I have a history of depression. Out of the blue his mom sends me a picture of a letter he sent and it said he did it purpose so that me and his mother would get to know each other more (we have very different views and he knows that). BUT WAIT THERES MORE we have a small group of friends that we do everything together. Well while he was gone the rest of us went to the movies and watched Ant Man and The Wasp. In the car, I sat up front with my best friend (she’s driving) and we started talking about him. They liked each other for a little while a few years back but went their separate ways. Turns out she had his address and they had been corresponding back and forth multiple time when I’ve only received one letter. I am raging at this point. Fast forward a few months and i can’t take it anymore. He’s able to FaceTime now so I finally decided to talk to him about it and now we’re in this huge fight because I’m mad about him writing to her more than me and he’s mad that I’m mad about something that can’t be changed. She and I aren’t friends anymore because she left for college and just stopped keeping touch. I’m so done at this point I’m fucking ready to call it. We’ve been on breaks because of her and how jealous I get around her because of their history.