My mom is cheating on my dad. What should I do? (They're seniors and I live 2 hrs away, but see & talk often.)

Stay out of it . Quite simply your mom is grown and it aint your business. It is your job to be a loving supportive daughter to both of your parents. Your mom is wrong for cheating and thier is no excuse for cheating but you have no idea what goes on in your parents marriage when you arent around and you dont know why your mom made the choices she made. Stay out of it , before it blows up in your face. Your dad could resent you for telling him.