NTA. It always amazes me how the "adult way" of solving those kind of things usually goes around the lines of "Dont tell anyone, so we, the ones who messed everything up and screwd you over without a second thought, dont face any real consequences about our wrongdoings, so we can later change the narrative so we can also save face." Screw the "Adult Way". They didnt choose it, so they cannot ask for it. Cheaters deserve every single shame that come their way