How do I re-become friends with the popular girl?

I just got out of depression over something like this. The best thing you can do is ask yourself, do you really want to be her friend? She doesn't sound like someone who values friendship that much--just the person. If she was a good friend, she would have confronted you about feeling ignored. You really should talk to her about this. It's no use getting depressed over something this insignificant. Tell her how you feel. Whose friendship is more important? Hers, or your other friend?