Most Helpful Guy
Time to bring out the big guns. Tell her you are sorry for accusing her of that and that you just love her so much and don't want to be hurt by her. You'd do anything in the world for her and would never do something as terrible as cheating on her and it was unfair to think she would. She is the best thing to ever happen to you and you know she would never break your heart like that. She's much too sweet and loving and amazing to do something so hurtful.
You see where I'm gettin at here?