My brother-in-law is always going on about his wild sexual conquests; lately he’s been telling

My brother-in-law is always going on about his wild sexual conquests; lately he’s been telling me about this married girl that he seduced into cheating on her loser husband. Apparently they’ve been fucking for months and the poor guy has no clue. The weird thing is, this girl apparently has the same name as my wife/his sister. Crazy, right?