In 1984 what role does self-trust play in Winston’s assessment of his sanity?

Until he is tortured by O’Brien, Winston trusts his sanity. Unlike most people in Oceania, he knows that history doesn’t change, 2 + 2 = 4, there are immutable facts such as the existence of gravity, and the earth is not the center of the universe. He trusts his own instincts for truth and what is right, and he trusts his powers of observation. He even begins to trust his memory. Self-trust is critical to Winston’s assessment of his sanity. When he says, “Sanity is not statistical,” he shows that he does not need validation from others to believe he is sane. When he is tortured, however, his trust in himself is broken as he betrays Julia. The end of that trust is the end of his sanity.