In a weird predicament...what to do?

To make things clear, I am not crazy.

My Girlfriend just broke up with me recently because she doesn't feel the same for me as she did more than half a year ago. She went to a trip about a month ago and returned differently; usually we would talk for hours, but she began avoiding me. Honestly, I didn't have a problem because I didn't like her anymore.
Things got weird after she broke up with me...I had this strong desire to be with her, for her to like me and it's been driving me crazy recently! If I had the choice I would try my best to not see her, but we go to the same school and her friends are my friends.
I have a feeling that if she begins to like me again, I would stop.
What should I do? I can't talk to her because the friendship is not the same anymore...I feel extremely sad.