There's definitely some light. You say you can't be like this forever, so there is only really one option! Knowing how horrible an ordeal it can be beforehand, and that huge desire to avoid it all, facing up to it is going to be really tough. I know. Man, do I know. I know all the racing thoughts and over-thinking!

Often once you're up there it isn't so bad after all, and often you can end up really energised afterwards. Maybe through having gone through the process and coming out the other side relatively unscathed.

Ultimately you're going to have to figure out your own coping mechanisms that work best for you, and maybe think, what's the worst that can happen? You come across as nervous? For the audience it's hardly going to be a big deal; maybe make a joke about it, at you're own expense! Have a laugh at yourself! Don't take yourself too seriously, for example. You'll still be able to present a professional presentation whether you're nervous or not, and it'll be likely you won't come across as being as nervous as you feel.

Maybe you can start yourself off gently; ease your way into it with smaller audiences for example?

Something I ask myself: what's the worse thing that's likely to happen? You appear nervous? Voice stammers shakily, and so on? It's no big deal! Really. And remembering to breathe property during the process - nice yet subtle deep breaths - this'll help no end, and help prevent a shaky voice.