Explain to them slowly and confidently. You're right, they're probably going to kill you, but not as much if you tell the truth calmly. They are most likely going to try to compromise with you, or go to the office to report the problems. They're going to try to change your mind.
To be honest, and I know it says no judging but I'm not judging. This is advice, don't drop out.
There are many, MANY, life changing and important people in this world that was bullied and went through a LOT of hard times. Emma Watson, Robert Pattinson, Tom Cruise, Miley Cyrus, Christina Augiellar, Bill Clinton, Tiger Woods, Demi Lovato, Kristen Stewart, Lady Gaga, Jessica Alba, YOU NAME IT. I can go ON AND ON.
But my fingers are tired.
Anyways, all these people were bullied and went through financial problems during teenage years and childhood. Look where there are now. A strong person ignores other people's jaunts and continues on with their head high.
Don't give up now.
Just ignore them.
Focus on your studies.
You'll show 'em!!
But of course, you can always drop out.