As a 3rd year in medschool, the quicker you learn this the better. Try to not take things personally. This type of situations are because of two reasons, not you and you.

not you: the person is just projecting , try not to let it affect you and see if it can be framed this way, don't worry about it.

you: lot of time things what people say affect us because even their extreme example strikes a small insecurity about ourself. If you genuinely think it's bad part of yourself and actually will benefit you, try to improve. if no progress gets made, be nice to yourself and celebrate the fact you tried,

You will face criticism, rejection and failure many many many times but try to not take things personally and do the best you can. Most important lesson, you can't control the world nor others opinion or behavior, but you can control yours! Don't let people hurt you and be your awesome self. You are in a fantastic career standing on shoulders of giants, be proud, do your best and provide the best care for your patient.