Ask him to make an appointment with five well-respected individual therapists or family counselors. Not even MARRIAGE counselors, just individual or family counselors.

And ask them if it's okay what he's doing.

M57 W 57; D30 D28 S24 S20 GD7 GD2 GD1 GD5m GD1m
BD 5/07; W's affair 5/07-8/07

At the end of every hard-earned day, people gotta find some reason to believe. (Bruce Springsteen)