AITB for being cross with my friend

A bit of information: Our school is having a function tomorrow and today was an off-day for the various participants to practise.

So today, while I was in the classroom, I get a call from my friend who just said "Hey, we need help with Practice. Can you come down?" Simple enough. I go down there and when I arrive, my friend tells the organizer "Oh, she'll be taking my place" and leaves. I ask him what it was about and he replied "I can't do this because I have to practise for the dance," and that was that.

I thought I was just helping with practise for today, that's all. But apparently, I'm supposed to take his place in the actual item tomorrow. I stayed until 5pm practising for the item and I'm supposed to arrive early tomorrow to practise before the actual function begins.

I'm quite cross with him because he dropped this on me the day before the event. He didn't even ask me to take his place, just asked me to come down and told the organizer that I'd be taking his place.

I wouldn't have minded if he did this like last week or so, they've been practising for weeks, so why would he switch with me just the day before the event is to take place? Why did he even stretch himself that thin?

I've been ignoring his texts because I just don't feel like talking to him right now.

AITB for being cross with him and ignoring him?