What should I do?

There is nothing to do. She's your teacher. Even if she was not married and 20 years older than you, nothing could happen because she is your teacher.

You can think about what you like about her but that's as far as it can go.

Just work hard, aim to pass your exams, and don't worry about being teacher's pet. I personally think that having a teacher's pet is the sign of a bad teacher. Perhaps someone pointed that out to her.

That's a very unhealthy way to deal with your crush.

You need to keep it a strict student and teacher relationship. On top of that she's 20 years older than you and can also lose her job if any actions were taken anyway.

Keep your mind focused on school and you can continue to think how you want but just know that nothing can happen until you graduate at least that is but even then, she'll probably be old and wrinkly lol. Just saying!

Its okay to have a crush on a teacher, even normal, but acting on those feelings is totally inappropriate. Keep those thoughts in your head, or cause you and her, a lot of EMBARRASSMENT