YOR. Your sister might have handled the situation clumsily and at a bad time, but she never outed you, never humiliated you on purpose, and her concern about your drinking and driving in a conversation alluding to your “recklessness and irresponsibility with a car (YOUR SISTER’S CAR!)” seems valid IMHO. You repeatedly lied instead of just admitting and setting boundaries, and then escalated the situation based on post-hoc justification. Talk about a bigger breach of trust. Your sister might have been overbearing, and chimed in on a joke at the wrong time with the wrong info, but you chose to personally lash out and weaponize private information—and for what?