Urgent help for matric dance please !!!

I was with a guy and we ended about a month or 2 ago and he wanted to take me to matric dance but didn't ask me. He asked if I would be allowed to go and I said yes but not to the after party and he said okay well then do you mind if I ask someone else🤷‍♀️ , and I said yes sure. It's 2 months before the matric dance and this new guy that I like (and he has liked me for a very long time )asked me over another girl and I don't know if I should say yes as my ex will be there and I don't want to ruin his night as he says if I go then he doesn't want to go ! Should I go ? Please help ! 😩😩❤️

Update : I'm not in matric ! This isn't my matric dance