If you had two friends that were turning to you to ****** about each other and ask your advice what would you do? I look at this similarly. You are incapable of being objective-no matter what you say. You are not expected to be. Your life doesnt need to be thrown into chaos just because they are having problems. And its a little more unfair than having two friends drag you in the middle. These people helped form the kind of human you are. They have profoundly influenced the person you are today. its like pulling the rug out from under you and its totally inappropriate. You cant pick sides and shouldnt have to. Tell them both to talk to each other and not to you. Repeat yourself everytime one of them tries to talk to you about the other. Walk into another room. Go out, or go home if you live somewhere else. Sound like a broken record if you have to. its not your job to give this thing a patch job. As much as you love and know your parents you only know them as parents. You have no idea how they are romantically and behind closed doors.