why do i fear?

i don't understand this thing, when it comes to writing something in english , i 'm really good . i have a good grasp of grammer and everything ( well except spellings ..:$) but on the other hand i toatlly suck at speaking. There's some innate fear that grips me everytime i begin talking in english, i get so nervous i make terribly silly mistakes , i stammer and all the vocabulary seems to escape me instantly .......i simply don't understand whats wrong with me? my younger sister who is just average in her english language skills, speaks better than i do ........ and that's why i am here, to talk and overcome this one big hurdle !!! will you help me?

Why do I fear?

I dont understand this thing... When it comes to writing something in english, i'm really good. I have a good grasp of grammar and everything ( well except spellings ..:$), but on the other hand I toatlly suck at speaking. There's some innate fear that grips me everytime i begin talking in english. I get so nervous that I make terribly silly mistakes. I stammer and all the vocabulary seems to escape me instantly... I simply don't understand what's wrong with me? My younger sister, who is just average in her english language skills, an speaks better than i do... and thats why i am here, to talk and overcome this one big hurdle!!! Will you help me?