I would tell him that i have factual info. when he asks what, tell him that you are not saying and that it doesn't matter anyway as you are done unless he totally cuts the cord from her.
But that is me, you do what you need to tokeep your sanity.
JAK
You don't get to choose how you're going to die. Or when, you can only decide how you're going to live now. ~Joan Baez