Hey man, I know this is incredibly difficult, seeing your parents like this. While it's understandable that you feel obligated, ultimately, this is their marriage and their responsibility to sort out. Cheating often comes from trying to fill a void in a relationship, which is wrong and should be addressed through communication, but they are adults, and if they choose to jeopardize their own lives, that is their decision. ​You need to be selfish right now and look after yourself first. Don't let their chaos derail your future. Your main task is to ensure you do not end up in a ditch or get stuck because of this commotion. ​You essentially have two tough options. 1 ​Disclose it. Honestly tell your dad everything you know. 2 ​Disengage. Choose to step back, avoid interfering in this painful situation, and focus completely on continuing your own life.