Boy does that sound familiar. I told my MIL the same thing and she told me I had to let my W go and let her be happy. Hello? Happy with her married boss that's her mom's age?
Just don't be surprised if you get a response like that. That's why I suggest being prepared for anything.
Your IL's could very well side with your W and make you the bad guy. Just be cautious.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.