I'm not going to attend a child's event with my ex-wife
What makes you want to avoid your kids event?
My ex is a bitch
I understand how ex's can be. However, you should be there to support your child for big events. What I've heard most people will do is keep their heads down and get through the event while only focusing on their child and how well they're doing rather than think about the ex at all.
What about me? Don't I matter? I have feelings. I just want to curl up into a ball and sleep when I hear these things.
You do matter a lot, and you matter especially to your child who loves you and wants to see you there. Would you have been happy if your father didn't show up to your events while growing up? Do it for them and not the ex.