It’s natural to be worried that your spouse might not be truthful in mediation.
This is another issue which mediators are trained to deal with. They’re trained to see if claims pass the smell test.
And if the mediator isn’t catching on, say something! Either say it in joint session or ask to speak to the mediator privately. Don’t be afraid to bring it up! Seriously!
And if you don’t trust the mediator with this information or you don’t think he or she can handle it, maybe it’s time to shop around for a new mediator……..