Did you 2 marry eachother's brothers or am I missing something here?

I don't really have any advice because your posts aren't very specific. All I clearly get is that your family adored you until the day she came along, and that she is 2 faced.

I'm also not sure why you need the family to call her out on her behaviour is there a reason you're not standing up for yourself?

Your family may not want to rock the boat and choose sides, especially not if its a closely entwined family. They may be more inclined to keep the peace and maybe even feel that you're a grown woman and that if you have a problem with her, then its your place to rectify the situation, not theirs.

I'm sorry if I misunderstood or misread the situation, but that's all I got for now.