We are all pulling for you. And we are all concerned. That's all...
I would insist he does it, talk to the OW I would go to the retreat And I would read Not Just friends, or the monogamy myth and go over the strategy and necessary things to be done with him. Dont let anything to just happen. Make sure he understands,this is his last chance and he needs to work in it.
If I remember correctly, it takes an average of 2 years to get over an affair and heal. He must be aware of that and agree to fight for you guys... K