[Pete.]

Don't worry about your age/name issue hun, it has happened several times on here and little problems have arised because of it

This 'friend' of yours is clearly jealous of you and the fact that you are more intelligent than you and that you are a nicer person than she is.

I would recommend talking to her less and spending less time than her until it naturally progresses to a time where you don't talk to her at all. In that time you should find a new, better group of friends.

If she continues to be unkind towards you (the dog comment is just sick) then I would tell the school because the chances are she is not just being mean to you but others. Perhaps there is something wrong with her personal life?