I accidentally act nice towards my flute teacher

I don’t like my flute teacher, I really don’t. She always ditches my flute class and lies about “I was at the orchestra rehearsal for the concert” even though she doesn’t or “I had a meeting” EVEN THOUGH SHE DOSENT HAVE ONE. One time I had a very important exam and she didn’t come to any of my classes. I even asked her to help me on breaks but she always declined. And when the exam time came I literally begged her to help me and do you know what she said? She said she’ll help to the first graders. I didn’t know how to react all I could do was get back to my classroom and cry. And now I don’t want to look at her face while I talk but today I accidently acted nice to her. And I feel bad now. Well shame on her!!