[Winman]

I would pray for him, but even more importantly, I would pray for his wife who is ill, as she may not recover.

Now, you could go to your boss and express your concern for his wife, perhaps even give him some salvation literature for her, and even ask if you could speak to her personally. Even though this man is being unfaithful, I am sure he has much love and concern for his wife. You never know, perhaps this will bring great conviction upon this man. It is possible they both may be saved.