Help with racist parents?

I have been married for 5 yrs to the most wonderful man and father and we have 3 perfect daughters together the problem is my parents still call my husband names and tell him hes not good enough for me eventhough he has a great job is a wonderful husband and father they can't accept the fact that is partially black. They call him ****** oreo mutt. thoose kind of things and i can't stand it and they would even pay attention too their granddaughters because the fact he is 1/2 black but looks white. My daughters all look white. I need help i can;t take it anymore how do i tell them too look past his skin and his dad.