Well, first things first, stop trying to police what she eats. That’s only going to lead to more conflict. Figure out ways to be supportive instead of confrontational. Also, you’re adding to her stress and making it more likely that she compensates by eating what you consider junk.

Why do I feel like you are leaving something out of your OP? What exactly did you say that lead her to threaten to lock you out? Also, you seem more concerned about the welfare of your expensive TV than your “fiancé.” You don’t mention at all where you’ve apologised profusely to your likely soon-to-be-ex for saying things that likely hurt her immensely.