We will always meet those kind of people who wanted to knock us down, in times like that it's important for us to not let them to take over ourselves. No matter what people say to you, you must know what is best for you. Sure, you can take criticism (just take those constructive ones) on board, you can observe their opinions that suit your needs best, but do not let anyone controls your mind and force you to be a different person.
I've been living that kind of life, sometimes a person can be a friend and a foe, as I've grown up, I only want to socialise myself with those people who will help each other sincerely, those people who have same visions as yours.
My advice is just surround yourself with equally kind and sincere people who won't dare to knock you down and help you become a better person each day. Wave goodbye to negative thoughts, people and views, and chin up and come back a stronger and more assured person. Just breathe, think of what will make you happiest and refocus.