It can take a really long time to get over someone you really love, you may never completely get over them. It's hard and its going to hurt, but at least you found out now rather than later down the road. Tell her to stop calling for a few months. Being friends with her right now will just be a constant reminder of the hurt and you need time to heal. Good luck. You're still young and there really are lots of girls out there, even if you don't think you want any of them right now.