Being clumsy does not mean that you're stupid - some of us are just clumsier than others and that has nothing to do with intelligence. And who goes around saying the kind of things people have said to you - people are unbelievable sometimes!!! They sound like a bunch of jerks to me and you don't need people like that around you. Reading your post, another thought came to mind, sometimes clumsiness can be a sign of a real neurological problem so you may want to consider seeing doctor to make sure nothing else is going on with you. Other than that, all you can do is try your best. I also know it's a lot easier to believe the bad things people say about you, but that doesn't make them true. Believe in yourself first and foremost!