Ask yourself calmly , are the criticisms fair? Can you learn and improve from it? if it is yes, then just take it knowing that they are just helping you to improve. Equally important, check what is the intention of the criticisms ? is it done in public？ does he/she critisize in a way that insult you when he/she has better ways to say it? If it is intended to put you down, you should fight back even if the critisms are valid. Intentions matter.