Come on man, you deserve better than that girl. She is a looser not you. She will realize it in future. Just pick yourself forget everything and get on your life for your parents.
Might be she was doing TP with you and she will realize her mistake when some one will do a TP with her.
There are plenty of girls there who are sincear and are honest. My best advice, you dump your feeling for that looser, go on with your life, get a nice job and marry a girl with whom you and your parents are comfertable with.
Remember your parents must gone a lot of suffering in getting you to a point where you are, so now its your turn. DOnt make them suffer becuase of that looser girl but make them proud with your achievements.