If they can feel how they want then fighting with your W is a possibility. They have a right to know what's going on when things are beyond concealment phase and a right to be treated as part of a family that is breaking up.
In the same way it is your duty to protect them, it is your W's duty to care for their feelings as well when faced with the questioning. Whether she chooses to lie to them or tell them the truth or any other approach is her perrogative not yours.
If she turns on them it si your duty to defend them but not much else. You are not your W's advocate and can't fight her on the one hand and protect her on the other.
