Martin - if you're here, and would want to continue speaking were it not for the physical problems you face - perhaps you should give beta blockers a shot? Side effects are uncommon, risks are low, addictive potential is low, so doctors are generally willing to prescribe them if the patient requests it.

It sounds like you're just experiencing stage fright. Many professional performers get this way, and beta blockers have been shown to help reduce the physical symptoms of stage fright(tachycardia, sweating, etc): https://pubmed.ncbi.nlm.nih.gov/6129674/

I had zero problem public speaking in school, or in casual public speaking (ie addressing participants in a sports league I help run), but I learned when I was 25 that I actually do have public speaking anxiety from a professional perspective. Perhaps it is because school/sports were low-stake activities in my mind, whereas I know that my professional performance is directly tied to my ability to support my family. So now I occasionally take a beta blocker before a big presentation, and they go as smoothly as my public speaking did back in college.