10 pts Is there any chance that I can win her back?

If she is with another guy there isn't a whole lot that you can do right now. You can though, tell her pretty much what you told all of us here, let her know why you were being y and stuff, all guys are like that and she should know. If you were only dating you shouldn't have gotten protective like a bf would. If you really like her let her know and ask her what she wants in a guy and search yourself to see if you are willing to accommodate those expectations of hers. Also do the same to her, it's only healthy. You obviously want her so go get her, just make sure you're sincere.