I'm kinda concerned here. Your wife is having an affair... does that not register? His wife doesn't know. Can you put yourself in her shoes for one moment and think how that might feel. You are promoting that. You are promoting her to feel used, deceived, disrespected, cheated of love and closeness, cheated of connection with her husband. She will likely feel betrayed in a way that goes to the depth of her being... like that of a child abandoned by its parent in their hour of need. They made a commitment to be faithful and he is destroying that with your wife. You are part of that. That commitment is usually meant to be sacred between a couple, regardless of whether or not "she won't understand." regardless of whether a couples communication has broken down so much that they are either not talking or blowing up at one another...
I can tell you from experience that the guilt and lying he is doing will far out weigh the sex and connection he has with your wife and you. That guilt becomes a disease to a cheating relationship. My memories of cheating, and that of others (if you have done some reading you will see) is of the guilt and lying I did... Mono will say the same thing I am sure, he cheated for two years and all he remembers is the betrayal he bestowed on his unknowing wife.
I didn't want to have to say this as I hoped that you would read more about others experiences. I hate having to dredge up this feeling again in myself about my own failure at having relationships that are healthy, loving and respectful... but,,, here I am. This relationship you speak of IS NOT poly to me. It is cheating. There is a huge difference. You have a flavour of what poly might be, but until you find a person to be in your lives that has some integrity, it just simply is not as far as I am concerned.
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