See... There’s a reason I don’t write an advice column. I would have told the dude to respond to the soon to be father-in-law as follows: “I wasn’t dating your daughter or anyone else when I dicked you down. You, on the other hand, were married with a child. If you say something, you damage three relationships. We don’t have to be friends, but we are ‘bout to be in-laws. You better learn to grin and bear it.”