You are not a mistake. No human being is a mistake, everyone deserves a chance to live a good life.
One bad comment or one bad parent or family do not define who you are as a person.
Their ideas about you are no more than their own projections of fears, insecurities and preferences -- you are not a mistake, no matter what they say about you. Be strong, stand up for yourself and tell people that you matter just as much as them.
Say it with us -- you are not a mistake.