A friend dealt with her martyr mother in law in a way that I don't believe is ehell approved, but worked after one time...
Martyr MIL would constantly insist that she would make the meal, she would host, she would buy, etc, then complain about how she was ALWAYS doing everything and it was SO HARD, etc. So one day, Friend looks at her, gets a "thinking face" on, and says, hey, would you mind doing something for me? MIL says what? Friend says "Would you mind crawling down off your cross? We need the wood." Then she smiled. Not one more complaint, and Friend got to host occasionally.