Your child is only a child once. Years down the road, kids won't remember the gift you bought them or the money you gave them as "payoff", but they will remember you being there and supporting their interests and activities. And you will be grateful that you went, or will kick yourself if you miss it (maybe not right away, but you will). I speak from experience, remembering all my activities my own parents went to years ago. And I see that in my own students that I teach today.
The Sioux will be in the Frozen Four again. They were just there four years ago. It's not like we go through decades-long droughts.
Things like this determine character. And any person who would put hockey, or any sport or event, above family is someone that I want no part of.
I commend you, GBpakrzz, on your choice (as tough as it is). You won't regret it.