Sunflowergirl raises a great point. How sorry is your own WS for the pain they caused the other BS?
In our case, WH was led to believe that OBH was OK with an open marriage. (OW herself puts this out there, so I believe it.) When I recently learned that OBH may not have been as informed as we thought, I asked my WH how he feels about being an OM, and wrecking someone else's marriage. He says he feels bad because OBH sounds like a decent, honorable guy, but there was certainly no sackcloth and ashes going on there.
Hell, many of the WSs we read about here aren't even sorry for what they did to their OWN marriage! These are just some sick, sad, broken people.