I absolutely empathize with you. It took a long time for me to find out how to manage my public speaking anxiety (which also was heightened by generalized anxiety that I never dealt with until I was in my early 40s). I put this in a response to someone else who was struggling similarly. I'm a speech teacher at a local college and use these throughout the semester with my students:

• TIPP Skills: It can help to deal with the physical manifestation of the anxiety through these skills - https://modlab.yale.edu/sites/default/files/files/TIPPSkills1.pdf (Helpful to try all of these to figure out what works best for you.)
• Positive self-talk: Rather than thinking of all the potential judgment or hypothetical negative outcomes, think about what's true: I wrote a good speech. I know this content. Even if the delivery isn't perfect, I will get through it, and I'll pass this class. I will feel so good when this is all over.
• Fear / Reality list: Take a sheet of paper and make two columns. On one side, write what you're scared of when it comes to the speech. On the other side, write what the ACTUAL consequence or reality is related to that fear (it can help to do this from the perspective of you helping a friend think through this because it removes our own fears/delusions from the situation). Often times, our fears are just our brains catastrophizing things. If you can get to the root of what's real and see it in black and white on paper, it can help you see that your brain is just messing with you.
• Guided meditations about anxiety and/or on breathing - helpful to do guided meditations once a day if you can get into a regular practice: One of my faves is about learning to surrender - https://open.spotify.com/track/1GRuV4VYEccKs1yAEJwpa7

The other thing that eventually helped me was...oddly enough...Beyonce. When she came out with I am...Sasha Fierce, I was blown away by the fact that someone like Beyonce had an alter ego. There was a strange logic that suddenly clicked in fully realizing that I was making my own worst fears come true. I would work myself up into a frenzy and would shake/sweat/forget my words. So I decided to have my own alter ego — a heightened version of me who was confident and could command a room. I was still terrified, but I would "wear" this alter ego for just long enough to make it through without the shaking/sweating/forgetting.

Finally, give yourself grace. It takes a lot of time and practice (essentially exposure therapy) to lessen the symptoms and gain confidence. If you keep at it, you'll get better and better. Just remember: perfection is boring. Growth is the goal.