I can definitely relate and sympathize and empathize with how you are feeling. For me public speaking became somewhat easier by just having to do a fair amount in undergrad and then for my job, but never really got great at it. Had bad experience with a boss really scrutinizing me teaching a class and it was my worst nightmare so I have changed jobs and will never work another job that requires me to do a bunch of public speaking like the past job. It may help if you can take baby steps and gain confidence presenting to 2 persons you know well then 3 and maybe volunteer and teach something you know well and can talk about endlessly.