Suppose you had written two letter's one to your father and second to your lover accidentally letters were exchanged what will happened to you and what will you do to convince the problem?

you could maybe be asked by your dad whats this about? Then you could take it and say I will throw it away! Your lover would ask you a bunch of questions, you can tell him/her that you accidentally gave it to you so he/she would give it back and he/she would understand.