I am a nerdy loser. What should I do?

So, I'm actually popular in my school, as in everyone KNOWS me, but I don't feel important at all. One of the people in the group that I hang out with hates me and wants me to die. Today, I bumped into one of the other people in my group, and I thought that he liked me, but instead of saying "sup", he said, "Oh, crap, you're here. I'm leaving.", and left right after. I feel like total sh*t now because now 2 people in the group hate me and the guy who insulted me today was my awesome friend. I think that the first guy convinced him to hate me or something. On top of that, my grandpa died 2 days ago and I'm so depressed over that. To add more depression to my life, I'm smart, but I can't even get into the advanced math cl. I can't even be NERDY right. I never fit in anywhere. PLS HELP!