Oh - and this is an unpopular opinion, but one I feel is a moral issue.
You said OW was married. So does this mean her husband doesn’t know about the affair? I know that I would want to know if my spouse was having an affair. Unless you have reason to believe the guy is dangerous, he deserves to know his wife is cheating on him. He deserves to have agency to make key decisions for his own future based on the truth. It may or may not be a strategic decision ( it could break up their marriage, making her more available to your H, or she might try to save her marriage ). But I think it’s just human decency that he deserves to know.
