Is revenge really a good idea? It may make you feel better, but think of the damage it could do to your relationship with your husband, your children if you and he fall out over it, not to mention the difficulties for him seeing the other child in what is already a very difficult situation. I think a little moral superiority on your account may be better - rise above her silly games, show parental behaviour instead of descending to the childish - I'm sure you husband will think more of you and be grateful you are being adult and part of any solution than being yet another problem....