Replying to NS!!! help needed

one of my best college buddies has a birthday tomorow and we're all going to the bar. 
But i have the option of skiing instead.   I already decided i was going skiing and i thought he would be cool with it.  So i told him tonight while we were smoking a blunt and he got all pissed off. 
So now i feel bad, like obviously i havn't skied in 3 weeks and im dying to go for 2 days, but i'd feel bad ditching one of my greatest friends.
what the fuck do i do??????
I feel like such a dick.  but i could go to loon, and mount snow!!??? ahhh shit nigga