I think my teacher told me I had misheard them.
What is it that you misheard from your teacher?
Nothing. I'm suicidal anyway, I was already pretty miserable
Taking an active role in class will help you learn the information, and it will keep your mind busy so it does not have time to be distracted. You may also need to train yourself to not be distracted. You got this my friend. I know you want to be better.
What if I get yelled at by teacher.
Then just have a private conversation and tell the teacher what you are going through and what you are planning to do so that the teacher knows in advance that you are just trying to change for the better. This way the teacher is prepared with your sudden change in attitude and I am sure the teacher will be more accommodating.