How not to care what others think?

i care, not because i am vain or think i am great. it is because i am extremely and painfully insecure. when i have not cared what others thought, i have been hurt. i shouldnt care what peole think but i do and, as a result, i come off as shallow (and maybe i am), which makes me even more unlikeable and ugly to other people and myself and makes me feel bad and the cycle starts all over. someone at my work referred to me as an annoying, vapid, ugly mess (not in so many words). i think people at my work feel bad for me because i AM ugly and insecure. i am admittedly obsessed with image, mostly because of my bad feelings about myself. i never judge anyone by the way they look, esp. not guys. i am as nice to people as i can be. maybe i come off as fake? i get so scared, i just dont know how to act now.