Everyone here gave horrible advice so far. How old is this girl - she seems to be very imature.
The girl who you are speaking with has very low self-esteem. She desires you, but does not feel that she is: attractive enough, at your level, etc. By bragging about all the guys that she has slept with, she is trying to demonstrate her "value." In her primitive mind, she wants you to think, "Hey, if a bunch of other guys find her sexually attractive and like to bang her, then so would I."
Her ragging on you being a virgin is a way to conceal her guilt of not being a virgin and boost her self-esteem. She definately wants you - but she is not long term material.
*The best way to counter act her bragging / ragging on you being a virgen is to ignore her. Simple. Just casually change the topic to something else. Thing about this logically for a moment, if this girl really had a problem with you being a virgen (as demonstarted through her hating actions), the she would not be hanging around you talking about sex. She likes you.
Another hint, if she was really BORED of ONS as she claimed, then she would not be talking about them. Think about it for a moment, when you are hanging around friends/girls you like - do you talk about boring stuff that you have not interest in...such as paper grocery bags? Of course not. You naturally tend to not even think about that stuff, but instead on things that interest you - hence; we can deduct that ONS interest her.
Another thing, if she were really BORED of ONS, then why has she done so many? For example, I find collecting stams boring. I figure this out after the FIRST stamp I collected and then stopped collecting because I realized it was boring. On the otherhand, I enjoy collecting baseball cards - so the action is repetitive - such as her ONS. She enjoys ONS. Another example, if you hated the food at McDonalds, would you constantly return for more of the same food? Of course not.
Don't try to defend why you are a virgen etc, because this will only make you look insecure.