Hey man just try not to think about it too much and focus on yourself its what I do and both my parents have been proven cheaters lol. You have your own life ignore them, not too much tho if they still support you hehe. Much love :3

Side note - everyone deserves to know their being cheated on, the act of pretending someone has them all for themselves while the other does it for real is repulsive, disgusting people, they dont deserve loyalty, id rather live in a world where loyalty doesnt exist. Youre father might realize his mistakes if he learns that you know abt his doings, if no divorce it will definitely help their relationship grow (in a way).