No, it will be boring, stay home and watch Game Of Thrones with a bottle of wine.
If you don't want to go, don't go.
Show up and slap them, then leave. Maybe set the place on fire.
Skip the fire then! LOl
Why let an ex fling stop you from having fun. I am sure they are going to have fun if you are there. I am sure there are many others that would love you to be there as well. Go enjoy yourself.
lol...then you have made your choice. :) But it was because you didn't want to go, not because your ex was there.