In a contradictory move, Winston goes against this awareness at the end when he refuses to agree with O’Brien. How does he do this?
I believe you are referring to Winston's realization that, despite all the torture he's been through, he still hates the Party. Even though he is writing the Party slogans that O'Brien wants him to write, he does not yet truly believe them. He knows also that feeling the way he does will only bring about more torture so he tries to squelch these feelings. He wants to love Big Brother and the Party so that he won't be tortured on one level, but he also wants to die hating Big Brother, on another level, so that he will have won that battle.