I imagine that, when you are in the public eye, being quiet and dignified can feel like being a doormat. Being silent on it does seem like letting him have his bread cake and eat it.
He made his choice to have an affair, she is entitled to respond as she sees fit and, unless it is harming anybody else, it is not for the rest of us to criticise. I imagine, if their son is going to be teased or picked on, it is likely to be for having a father run off in such a public way, rather than for this.