I agree with what Christina said (I usually do.)

I would step back and limit interactions with the girl and turn your attention to something else in your life as much as you're able.

In my experience, the kind of feelings we experience after a romantic rejection have a specific "shelf life" or length of time that they will exist. You are grieving now and then you will begin to heal from the loss.

It's a painful feeling, but it's nothing to be embarrassed about and it won't last forever. It's okay to let yourself experience the feelings fully.