I don't agree with the DB counselor. As Nop said, these relationships don't usually survive the light of being revealed.
I don't even agree that it's "coercion." You're not coercing her to leave him and come back to you. You're presenting consequences to her actions -- her bad actions. This was HER bad decision. What are you supposed to do? Just wait for her to come back to you? Sorry, but this doesn't appear to me to be a very proactive plan to save the marriage.
