I agree with much of what Aquarian has to say about the 180 bit and not walking away from the discussion.
I do think that what you wrote here
Quote: I walked out, because I was about to say a lot of things I would later regret, such as, “it’s not a duty, but that really says a lot about your mind set” and “what do you mean we’ll ‘go back’ to your being bitchy all the time?”
is probably not how you want to say what you're feeling. What you have here seems more designed to hurt her than to communicate with her. Stay in the fight, but stay in it to communicate your feelings to her, not make her feel bad. So what can you say that communicates what YOU feel when she says it is a "duty?" What can you say that communicates that her behavior is unpleasant a great deal of the time whether you bring up sex or not and that you'd like to know what is causing it? What can you say that keeps the exchange a communication exchange rather than becoming a verbal fist fight?
As for any behavior that is reminiscent of adolescence (eye-rolling, disgusted sighing, etc.), knock it off! If your W were here I'd be saying all this to her too, but she's not. You're the one who is going to have to start the ball rolling toward adult communication. You can do it. Stop yourself from saying things designed to hurt her, but don't stop yourself from constructively communicating what you are thinking and feeling.
