Please help im not stupid!?

i am sick and tired of people calling me ditzy dumb and stupid.ive been called these names every since i was like idk 10 pretty much my whole life....if you knew you would know that i have never given a **** what anyone has ever thought of but this to much...it makes me so upset when people call me these names idk why people who dont even know me on a personal bases think that im dumb or stupid on a first name basis or even first impression idk what to do please help tonight when my best friend told me that her boyfriend hates me because he doesnt like dumb girls for some reason made me really upset and im crying and really sad please help=( how can i be myself without people calling me these names?