Mother-in-law is tearing us apart! Help!?

My mother-in-law is slowly but surely tearing us apart. She has made several comments about my race and what she calls my immaturity in life. Bear in mind this lady has never had the decency to try to meet me. She refuses! She has tried to turn my husband's family against me and when that didn't work she made it all about her and saying that her family has chosen me over her. (which they haven't because they are not close to me at all they just chose to not in). She made comments about how I'm ruining the family and she has said things about how she won't like the race of our children. (He's white and I'm black). My husband and I get into it about this all the time. He has never stood up to her and she believes she can say these things to him. I don't want to live in this place of malice, but his inability to confront her hurts me. What's worse is that he doesn't understand why I should be upset about it. Help please!