Why does my teacher act like this?

[yo momma]

My teacher is always picking on me. She tells me that I'm annoying and that I'm a troublemaker, and that she could take me on. Then she tells my friends that they shouldn't be hanging out with me for that reason. When they're not around, she's all sweet to me, and she even lets me call her by her first name. Then she told me if I ever ended up in jail she would come see me. She's always laughing at things I say, and touches my arm. She also gave me an "excellent student" comment on my report card. Well come to find out, she's having an affair with someone. She told me that it was her friend, and that she was talking to him about me, saying it was funny how I got in trouble, but I don't know why she'd tell him that.
12th grade