My best friend is a jerk, and has been forever..?

It doesn't sound like you two are really friends. You're more like acquaintences. You hang around some of the same people and get along ok, but you don't seem to really connect like friends should. So write it off as that. If you see her around great, if you two talk then fine, but don't think she's your best friend because she's not. Keep it in perspective and it probably won't bother you as much.