Replying to Anybody suck at public speaking?

This is a relatively stupid thread but whatever I'm just gonna rant. So today I had a debate in history on the American revolution and I had to give my part of the argument which lasted for about 4 minutes. The first half of the speech I did fine but then everything went to shit. Halfway through my part it just got progressively worse and worse, I could hardly pronounce words, you could hear my voice literally tremble, I was shaking, and my heart was beating out of my chest. Anyways this is something that I've had to deal with my entire life, and it just sucks cause everybody knows I suck at it, and it's something that I know I'm gonna have to do as an adult. People always ask me why I'm not afraid to do flips on skis, but look like I'm gonna die when I speak in front of just 10 people, and I never have an answer for them. Sorry to be a little bitch on NS, just wondering if anybody has the same anxiety about speaking publicly, or if any older members had any advice for me?