Am I wrong for not wanting to be seen around her?

I have been friends with this girl for 4 years, and we have had many problems. But recently, shes been dressing....to be honest, very slutty but not really revealing. Shes obese technically, but not really big actually. But she usually wears booty shorts and fishnets and stockings. And also she really isnt a clean person, and its beginning to be disgusting. Like she has nappy hair (shes white) and she wears trashy makeup and obviously doesnt care much about hygeine. I know this makes me sound mean, but i dont want to hang around her anymore. I was dressed really nice today, but she completely offset that by wearing trashy clothes, once again. Everyone around the school (and i literally mean everyone) were turning their heads and talking about us. And i hate it, im beginning to be paranoid about it. Were freshmen, (i want to make a good impression) and i dont want people to know me for who i hang around, and ive lost friends because of her. Is it selfish not to want to walk around and hang with her as much because she embarasses me so much?