Something that helped me recently was contextualizing my desire to live as the other sex to be just as unfulfillable as joining the NBA, getting elected as head of state or becoming a billionaire. It's just a silly little fantasy that is not worth thinking about much. Truth is that even if you could pass (which like 90% of us can't), "IWNBAW" will still forever be true, and that's fine, the same way it's fine that we're not all billionaires. You don't need a perfect life to be happy.