I'm pissed because my friend totally bailed on me....?

So my best friend (who is a guy) totally bailed on me to go to a party with some random guy he met, even though we've been planning a fun night staying in together with each other for weeks. I'm pretty pissed. And the worst part is, when he got invited he didn't even ask me if I'd like to go. He just left. We were supposed to play games and drink margaritas and watch SNL. This is ridiculous, we never get to spend time with each other because we have such weird schedules. Do I have a right to be angry?