One of my friends got in trouble for no reason today, and I'm really mad about it?

Okay well Today One of my friends had fallen asleep in class and this Mean Teacher Assistant saw that and yelled at him "Hey! SIT UP! If you lay your head down again I'm Gonna send your IDIOT self to Another Room! I'm gonna let you play Basketball with me! And I think you know what that means! I'll bounce you!" And then he gave him a angry look.And then, my friend got tired again and then that Mean Teacher assistant got mad AGAIN and said "I said for you to SIT UP AND STOP FALLING ASLEEP!" And then that Mean Teacher I have said "Since you keep falling asleep Stand UP!" And then he made him stand him for like a hour and then my friend said that his legs were starting to hurt and then that Mean Teacher said "Deal With It" and I got so mad when I heard that.And then, after he finally got to sit down again, he felt so tired after standing up for so long he laid his head down, and then that Mean Teacher Assistant said "Okay that's it go to Mrs. John's Class!" And then he got up and he could hardly walk because he had stood up for so long and then he said "Sir, My legs hurt, can you help me carry my stuff?" And then That rotten Douchebag Assistant said "NO! You can carry your own stupid stuff you Loser! And you better start going to sleep at night so you don't do this bullsh*t in class!" And then my friend struggled to walk out of the Room because of his leg cramps and then before he could get to the class he fell down in the hall because his legs were getting really weak, and then that Mean Teacher Assistant heard him fall and then Angrily walked out of the class and starts yelling at him out in the Hall for "pretending to fall" and then said something racist to him.My Friend begged him to help him up but that Mean Teacher Assistant told him to get up Himself and then Angrily sent back in my class.My Friend then called for help outside and Then I sneaked out of class and helped him up, and then this nice teacher named Mr. R came over and helped me to take him. To the other class, and then after that Mean Teacher Assistant got mad at me for helping him and then threatened to suspend me if I did it again.Mr. R then told him what I was doing was right and that he was gonna give me the good student award.That Mean Teacher Assistant ignored him and dragged me back into class where he embarrassed me in front of everyone and said I was helping "that idiot mark" outside and that I was a "idiot" as well.That Mean Teacher Then said "He is such a idiot for helping that Boy and going out of class, If he does this crap again I will give him silent lunch for the rest of the week" And I got so mad when he said that.I am really tired of these teachers Bullying me and other students, what should I do?