Unfortunately time is the main thing that works for that. Until then use lots of distractions. The happier the distraction the better. And process your feelings through writing/journaling. That can help a lot.
first you didnt mention if she loves you. But without knowing that, its called grow up and stop being a whiny *****.
i've been there.
Time will help, as long as you're not around her.
Move on. You'll find someone else to obsess over soon enough.