I think I am with fb2 on this one. I too look at the "pop-psy" advice we get today and while I understand the basic motivation, I still wonder where you draw the line here. At what point does the behavior of the other parent become so harmful or outrageous that you have to call a spade a spade here even to your children? Larceny? Armed robbery? Murder? Serial Murder?
I know some of you will make the obligatory and tired argument that neither infidelity or D are on the same level as said capitol offenses. But you have to agree at some point one needs to draw the line or else you might as well admit to having no value system to live by and model for your children. There is a point where the elephant is in the room and no one can deny it, and thus defense of the other parent's reputation then takes a definite back seat to guiding your children towards valuing moral integrity.