Should I be mad?

How old are you?

So basically I messaged my friend to check we were okay for the plans we made for this weekend. I was out with another friend who is no longer friends with this one and she said she wishes they were okay so I told my friend and she felt bad and mailed her so they've sorted stuff out. My friend asked if I would mind if the other friend came at the weekend I said not to sound mean but yes if rather she didn't cos my best friend is going on holiday for a bit soon and I'm moving soon I think, she totally respected that and said it was fine. Next minute there's a group chat the two of them are making plans for the weekend when my bestie is already going with me so now she's took it all back and the three of us are going together. I'm so angry but should I be?

Why does this matter is this your way of saying I'm being stupid

Yes. but you allowed yourself to be dragged into a group of 3 when the idea was that you were going away with your bestie only. If you all now get along then you might as well go away together on this occasion but time next be more firm snd boundaried about what you actually want. And don't get involved in friends fall outs with other people unless that ask you to- it just gets messy!

Yup