Your stepsis convinced your wife to fuck stepsis's husband, w/ you overhearing them talk about it. They deny your wife cheating, w/ them insisting it was just a joke.

Your wife Amy is in tears, begging you that she would never betray you, while she secretly enjoyed fucking your stepsis's husband Mike. Your stepsis Joanna says you are still the whiny little stepbro she remembers from childhood, w/ her disgusted that you are causing stupid drama over some harmless joke.

You really should apologize for eavesdropping on the private conversation between your wife and stepsis. Let the girls have their fun w/o you barging in and misunderstanding the situation.