Then that is what you should be looking at. Not that the whole class is racist or hates you for you grades (although I will say that I can't stand the grade tellers and askers. Us fellow students aren't proud of you like you parents are.). It sounds like something went down in that group project for whatever reason. Maybe you accidentally insulted someone. Maybe you gave the impression that you'd do something and then you didn't do it. But if you have a specific point in time where things went south, something happened.