Sometimes we don't get along...

There is a girl on my cheer team that I just really don't get along with. I won't reveal her name because she doesn't really know that I am doing this about her. She is just one of those people that is silent all the time until you turn your back then she's super talkative about you. I know that she's not like that with everyone and that she has friends and they all chat and have a good time, but it seems like she has some sort of vendetta against me. I want to fix that. I know that I don't really get along with her because she kind of screwed one of my friends over and took her boyfriend, but how does that involve me? I feel bad for my friend but this other girl (lets call her Spring) didn't do anything to really insult or hurt me in any way. She is genuinely a nice person towards me so I don't know why I'm so bent out of shape because of  it! I really need to be more objective towards Spring and hopefully it will change my attitude about her.