Welcome to the bb forum.
I believe I could literally feel your fear as I read your post. You are certainly not alone with your anxiety.
My first thought is for you to consider vaccination against Covid. It’s entirely your choice, no judgment, but it might help to relieve your anxiety and it will definitely protect you from serious illness. I have had two doses now and feel a great sense of relief.
I would also encourage you to talk to your Principal about your concerns and ask to see the school’s Covid risk assessment. It could be that there are other control measures that will be implemented to keep teachers and students safe that you are currently unaware of.
You could also speak with Safe Work Australia or your State work safe authority to seek advice and reassurance about safety in school environments.
And, if you’re still not satisfied and not comfortable returning to your workplace, I’d recommend that you ring Fair Work to find out what your rights are.
Happy to keep talking. Kind thoughts to you