I will faint from nervousness someone help

I gave my name up for a speech competition and I have not given a speech in front of a huge audience in the past 4 years I developed extreme social anxiety to the point where I was unable to talk with my classmates as well without physically shaking it was bad I still have social anxiety but not that extreme anymore. Now in 5 days I have to do a speech in my college HALL omg why did i sign up for thissssssss i can't back down aur meri gand phat rhi Hai pls koi kuch tips wagera de de kuch Batao mujhe. Some tips so that I don't start crying infront of everyone