Bit of a tough one - feel for you. I agree with FN keep rising above it. Avoid one to one conversations if possible - try to make sure someone else is present when talking to her (so you have a witness!!) Have found this invaluable when dealing with my ddil. She has a tendency to tell it how it isn't, if you know what I mean and this has caused problems obviously. I try to keep conversations on a small talk level and sympathise and agree with her as much as possible. It is hard. 
Huge win for Andy Burham, Reform a distant second - where to now?
