It may be true that your behavior around this mare has some influence on her behavior. Perhaps a lot. But, I have known horses behave a bit worse around nervous, fearful or passive persons, but not THAT badly. That is just terrible behavior. I agree that you and she are a poor match. I wonder how you ended up with such a horse.
If you do go shopping again, look for an older gelding. Usually, they are milder in temperament, though I know this is not a 100% true thing.
This is't you "fault" so stop blaming yourself.
Stick with the things that bring you pleasure wit horses. There is no requirement to actually own one to be involved with them.
Good luck and check in from time to time and let us know how its' going.