Some people criticize and put down other people to make themselves feel better about themselves.
It takes a really heartless human to do this to their own child. Try and remind yourself that she maybe doing it because of a fault in herself, and it has nothing to do with you, therefore it is something you don't have to take on board.
I know it would still hurt a lot, but as PugofCrydee suggested, try and find someone to spend your time with who will give you support instead of putting you down.