Here is an invaluable tip I learned years ago that works EVERY TIME! I was in a situation where a certain in-law would say unbelievable things about my religious beliefs in front of God and everybody = ) Usually large family groups on my husbands side of the family who were all of a different faith. This what what my shrink told me.
Whenever she says something, or anyone says something that is out of line, you might try looking at them, pause as if thinking about what they said...and then reply...
"Well, that's an interesting (comment/statement/question) (insert person's name), I wonder why you would (say, ask) that?" and then wait for a reply. It works wonders, and is a way to respond to such behavior without stooping to bad behavior and it also allows the individual to think about what he/she said.
