What to do when your old best friend has changed?

hey y'all. Ok so I used to have this best friend...lets call her sue. well sue has now turned into a sl*t and i can not stand her, she is rude acts like she hates me, and she is just a plain out bi*ch. But our moms are best friends, so what do i do? i have to see her almost everyday and i hate it, ive talked to my mom about it and she doesnt know what to do. All of my new friends hate her and her and her Copy Cat..lets call her jill, well jill is just the same...and jill and i are in the same situation..old best friends, moms are still best friends. so what do i do!?