My best friend has started hanging it with another girl and calls her her new best friend? I hate it

We’ve hung out before but once my best friend isn’t speaking to me. She’s been hanging with our other friend and she calls our friend her new “best friend”. I don’t believe this! I wish my best friend would forgive me and talk to me about her problems. I get so jealous seeing them hanging out together. She’s MY best friend and I feel like that other girl is taking my best friend away from me. 😭😭😭😭😭😭😭😭😭😭😭😭😭