Failed my driving test....?

-I failed my driving test because 2 lanes were merging into one, there was a car in front of me who slammed his brakes and was going to turn right. I slowed down obviously (i was like 2 car lengths behind) i checked my blind spot/signaled because of the 2 lanes merging into one. So i checked my blind spot for a second maybe and the guy starts screaming and takes the wheel and slams the brake (it was a drivers ed car) when i wasn't even going to hit the guy i had half a car length. He was saying KEEP YOUR EYES ON THE ROAD and was yelling like a ******* child. Is this fair? I don't think so and i did everything else perfect. I believe i should have been a bit further back, but he slammed his brakes.