A: It depends on you. If it were me, I would just ask her, because I'm very straight forward about things. If you are not, then have a friend find out for you. Are you guys friends? It just depends on the situation.
A: I would say F*** it, because you obviously don't deserve to be with this girl, because she dumps you for this loser. Just look around, and you'll find the perfect girl for you, who won't do things like this to you. Don't worry, I'm going through the same thing. =)