I just re-read your post.
I don't think you're bipolar. Relationships are hard to get over and you are probably just a little depressed. It takes some time to get over a relationship.
I don't think you're bipolar though, but I'm not a doctor and I'm never around you.

Try finding something else you enjoy like art, sports, videogames, ect. to try to get your mind off things.
Hang out with your friends, and don't talk about your ex.
Try to avoid anything that might get you thinking about her. Don't talk to her or about her.
If you find yourself thinking about her think about the bad things she did to you or think about something else.
If she goes to the same school ignore her. Avoid any contact with her.

This is how I get over my ex's.

Anyways, there are plenty of fish in the sea.

I'm not sure if this would help you, but go talk to a therapist or counselor.