Time heals. It's slow and it's painful but it works. Talking helps, going out with other people, seeing friends. She'll be like a book you read long ago. If you trust that if it's meant to be then it'll be again, and if it's not you will wake up one day and realize that you hadn't even thought of her once. And then you'll be free.
People always think they know other people, but they don't. Not really. I mean, maybe they know things about them, like they won't eat doughnuts or they like action movies or whatever. But they don't know what their friends do in their rooms alone at night or what happened to them when they were kids or if they feel sad for no reason at all.