My take on these sorts of things is to neither ENcourage nor DIScourage family (or friends) from doing what they want to do, and what feels genuine to THEM.
My D-then-18 wanted to call my wife's OM, and tell her what she thought of him. I told her I would neither give her his number, nor forbid her. Same thing with what she wanted to tell her mother.
Consequences. Your position should be "I have decided that I will no longer lie to cover up your affair."
