Hey 1z, Congratulations, Becoming a teacher is wonderful. The fact that you have made it to Grad School tells me you have a lot going for yourself.
I agree with the professor, you should not tolerate bad behavior from your students. What is wrong with kids speaking to their teacher in that way.. If they want better grades, they need to earn them Geeze.
I seriously think you need to give yourself a lot of positive affirmation. And take it seriously.
I think it is sad that your brother has chosen to pick on you for any and everything about you that he disagrees with. Your friends are your choice. What does their color, or where they grew up have to do with it! Maybe your brother wishes he was more like you! It sounds like he is very insecure himself.
Like I said before, stand up for yourself and do not allow anyone to treat you badly. If others can not treat you like you deserve to be treated, with decency and respect, shine them on!!!!
Look at yourself in the mirror and tell yourself you love yourself and do it everyday!!!
Good luck to you