Why do people always take my anti-social ways so personally?

They feel you're saying they're not good enough or something is wrong with them. I don't understand why you're worried about this so much though because as you said 'high school yeaars are a very insignificant part of my life." If you truly believe that, then it really doesn't matter whether people are calling you two-faced or not. Nothing they call you or do to you matters. Nothing you do matters. Just do whatever you want basically and not worry if you truly believe it's completely insignificant. I personally think your high school habits and personality traits will never go away so whatever you develop now will stay with you forever.