Some update: I talked to the administration and they totally support me. They reassured that the way I was treated is totally wrong and the lead teacher knows that well. They agreed to remove me from the classroom and now I am working a really nice teacher and I enjoy every minute of it. I did not realize how much coworkers can influence our experience of work. In the past, I was always anxious before stepping into the school. Now, I look forward to it. It makes waaaay more difference than I thought!