Which party should I attend?

I know this is a pretty stupid question to ask, but I can't seem to decide. My best friend decided to plan a final party before she leaves for FL this summer, the last time I'd see her, as well. But, my mom planned out my aunt's son's college graduation party the same day. I don't really know what should be my priority. I mean, if I go to my aunt's party, I'm not going to be doing anything but sit there because I'd be the only one my age. But if I don't go to my best friend's party, then I'd never see her again. What should I do?