I think its pretty rude that she said that about you, especially within earshot, I mean just because your quiet doesnt mean its something that needs to gossiped about. So what if you are. I know its hard to do, but I wouldnt waste anymore time thinking about her. Some people are just not going to like you, for no reason at all, blinded by bias and prejudice... people work out in their head what kind of person they think you are without actually putting in an effort to find out for themselves. Try not to let her get to you... you have a friend there who likes you... and you seem like a nice person to me too.