You've certainly identified the thing you fear the most - aniety, but have you made a list of all the things that might go well? Visualize your ideal situations and returning to school will become less scary to you.
I was the same way in college. If you set yourself up to have a bad experience, you'll have a bad experience. Give yourself good expectations and plan for those.
And as i've recently learned "every master was once a disaster." success is always preceded by failure. Just keep going.
Kindly,
Kitt