Ughh that's terrible. And what a position to put you in, as well! What exactly does she expect you to say to that? (Although I quite like the way in which you responded!
)
I've had several similar situations. I went with a friend to visit her mother and she commented first about my achievements (for an extensive amount of time), and then proceeded to question my friend in front of me about her lack of achievements in that department. A similar thing happened with a cousin of mine and one of our great aunts.
I just don't understand it. I cannot ever imagine opening my mouth up and having those words come out. One really has to wonder whether these people feel like fools after saying things like this. Apparently she didn't, as she went on to comment about your friend's weight to HER afterward!