How would you feel if you found out your ex is taking a girl on a date at the same place he took you for a special occasion date?

Me personally:

I recently found out mine is taking this girl he likes to a Yanni Concert in Boston. The same one he took me as a birthday surprise gift knowing how much i like this kind of music. I feel both amused and a little upset as he is using the same event to get somewhere with this new girl. Worst thing was that i was already planning on going to meet Yanni backstage.

Also even tho we split we aren't in a bad term.