simple..take a personal manners class for her..I think she won't bother you after that..

I know how annoying it can be, I teach for a living myself except in the military I can make my students do stuff so they won't dare make a sound.

wtf? How does that happen? We need more info, OP.

Why not correct her, and let her know it's your class?

That really sucks. I would have just yelled at her to leave. like after the first couple times wouldn't she get that it's not her class?

cheer up buter cup. try teaching a class of 19-38Y/O's They can be ruthless. Just keep telling yourself it's YOUR classroom and they are learning from YOU. The only difference is I could cuss my class out and make them do pushups if they didn't listen. Good luck OP. I'm sure you are a great teacher.

You're gonna have to grow some thicker skin in your career. Kids are brutal

Take her to one side in the teachers' lounge and politely tell her that her behaviour was unacceptable. She was undermining your authority over your class and making you - not just herself - look stupid to the kids. You need those kids to respect you if you're going to get anywhere teaching. Don't be mean about it, but make it known that if she crosses that line again you'll be speaking to your superiors about her conduct.

Why did u let it happen, it's your class u should have straightened her out, u just lost the respect of your students and with that control of your class and your ability to teach them, u need to remedy the situation quickly, op

Talk to your superiors about what happened, ask for them to inform the other teacher of where her class is being held, hang a list of teachers with their class numbers and a map of the school on your door (incase others forget as well) and lock your door so you don't have anymore disruptions. I had teachers who would lock their door 5 min after class started and wouldn't unlock it until the end of class.