My best friend..

Little rant… I told my friend about this guy I was casually seeing. I told her how amazing the sex was and joked around saying “if only you could experience it” well this girl took it literal. She’s been texting him behind my back and agreed to go fly to him to see him. Crazy thing is, he was the one who told me (we were friends before we hooked up so we talk every day) and I was dumbfounded. I confronted her about it and she said she was drunk and wouldn’t go see him but I’m like we’ve been best friends for ten years and you didn’t even tell me you guys were talking? When you saw I went on vacation with this man. I don’t know how on earth someone could be comfortable having sex with their best friends most recent sexual partner & not even talk to me about it. Like at least wait until I’ve seen someone else lol. Ugh now I don’t want to talk to her and she hasn’t apologized