LOL Johnny! I have a phone number some scary guy who walked up to me in the middle of the street gave to me when I was 16--his name that came with the number was 'Lestor the Molestor'!! (shudders at the bad memory).
As to the topic at hand:
I actually had a very similar situation back when I first started college quite a few years ago. I do not know how you felt about this girlfriend, but I was crazy about mine. When she cheated on me, I forgave her, figuring everyone deserves to make at least one mistake.
However, when she (falsely) accused me of cheating on her and began harassing me, I officially and publically (she was yelling at me in the middle of the campus) broke our fling off and severed all ties.
The cold shoulder worked like a champ! After a short time of her making an ass of herself with no response from me, the stopped having anything to do with me.
Now that I think about that girl, she was a real "B" with and "ITCH"
Hope everything goes well with you!