Most Helpful Girl
Was she kissing with or sleeping with the guy or just hanging out? I mean since you flipped out its not getting any better if you contact her. You can say you're sorry for being angry at her, that's a start. You can just be friends with her but I'm not sure if she would get back with you because you reacted so badly, I think girls usually don't like when their bfs are too possessive. And that she is seeing a new guy, that's not a good sign either. Maybe try to stay calm and just say you're sorry and that you're still her friend if she needs. Maybe one day she would come back, not at the moment though if she's seeing somebody else.