Some wisdom from the ancient Stoic philosophers, on how to deal with unfair criticism:
"Does another do me wrong? Let him look to it. The disposition was his and the activity was his." - Marcus Aurelius, Meditations 5:25"If you learn that someone is speaking ill of you, don't try to defend yourself against the rumors; respond instead with, 'Yes, and he doesn't know the half of it, because he could have said much more!'" - Epictetus, Enchiridion 33:9
"Remember from now on whenever something tends to make you unhappy, draw on this principle: 'This is no misfortune; but bearing with it bravely is a blessing.'" - Epictetus, Fragment 28b