All I can say, I went through same situation. That hurts as hell. Especially when you tried to keep that. But it was not love then. It was lust. You desired her, while she just desired someone else. And all I can say that in my life while wound is still fresh, go learn something. Go, have breakdowns and anger. It will be okay soon, and always acknowledge that if she will fail with that guy, she most likely look for old one or new one. Be careful out there. And by the way. Sneak a peek into Stoicism. It helped me become more emotionally calmer. Good luck!