I'm sorry you are faced with this anxiety-provoking event. It's been many years since I was in school. (There was no such thing as on-line school back when I was attending.) I was never much of a student & often showed up less than prepared. Plus I never cared much for any of the teachers I had back then either. I can still recall the anxiety I'd often feel going to class.

One thing that may help you is to simply express your anxiety to your teacher. Don't tell her it's because you don't like her of course. Perhaps you can just say you're having a difficult day, or something else generic. Sometimes just being open about what you're feeling can help. And then, beyond that, from my perspective it's simply a matter of acknowledging to yourself that you're anxious, & allowing it to be there (because it already is.) You can then, perhaps, visualize yourself breathing into your anxiety & you can smile to it. You might even place a hand over your heart as a sign of compassion & lovingkindness for what you are feeling.

Here are links to 2 articles, from PC's archives, that (hopefully) may also be of some help:

3 Deep Breathing Exercises to Reduce Anxiety

9 Ways to Reduce Anxiety Right Here, Right Now

You can do this!