INFO: how did the conversation actually happen?

If she raised the issue and wanted you to cancel the trip that’s one thing, and she’d be wrong. If it came across more like ‘you’re an obstacle to my fun now, so I’m replacing you’ then I think most people would react pretty negatively.

Her response sounds unreasonable without context, but if it was always a trip that you two had planned together and she was fully intending to still go and you not only asked her not to come but told her you were going to swap her out, I can see why she’d say what she did.

It’s not unreasonable to want the trip that you paid for to be what you want it to be, but depending on exactly what happened, your friend’s response makes sense too.