M.D.
I'm going to play devil's advocate a little bit with you here. You say that you want to be friends with her, but it's clear that you disapprove so fundamentally of everything about her, I suspect that comes through in your interactions with her. You stand in judgement of and disapprove of her clothes, the way she spends money, her friends, how your brother treats her, and her relationship with her parents. Was she supposed to pretend that she wasn't friends with someone just because you had a falling out with that person years ago? Rather than accept her for who she is, you would prefer to change who she is, what she wears, how she and her husband spend their money, how she interacts with her husband and family, and who she is friends with. You say that you are trying your best, but I doubt you can hide all of that.
Given that it's clear that you just don't like her, I think you should give up on the dream you have a of sister-in-law/best friend, and accept her for who she is: someone you might not choose as a friend but who your brother has chosen. If you can respect her life choices as her own without the negative judgement and respect her as your brother's wife, you might be able to work on a better (although probably never very close given your very different priorities in life) relationship in the future.