You're her beard! Give them enough rope to hang themselves. Let them work it out between them. His wife can go along if she wants, and watch their sexual energy, and mope around in her fog of not knowing for sure (denial, not just a river in Egypt), not admitting to what is staring her in the face.
I don't disagree, I'm just not there, yet.
One additional detail, my mom, aunt and family friend are going to the same event tonight. I don't know if we'll run into them or not, but my family isn't stupid when it comes to this kind of thing. In light of my mom's current problems, I need to be my own beard too.