your professor is right.
nursing instructors, especially in the first few semesters, will push you. they will push you harder than you ever have been pushed and have ever wanted to be pushed.
i think this is because that when you are a practicing nurse, you will be pushed, physically and emotionally, everyday. they want to see your heart is there and that you will not buckle under the pressure.
i had an instructor who rode my butt like nobody's business and the more questions i answered right, the harder she pushed. she would come up with stuff i'm sure she had googled or something and ask me in the most condescending way and give me the absolute worst patients and the worst assignments and diagnoses to research. i never cracked. but she tried. she told me when it was all over that she expected more from me, because she knew i could take it.
my advice is to do your reading, study like you've never studied before, and BE PREPARED for class and clinicals. hold your head high and if you don't know the answer, find out. always know why. see that goal and make it so close you can taste it. make it real and stay focused...
you'll do fine. when you feel like you can't take it anymore, lean on your support systems. breathe, relax, go for a run, whatever works for you--and KNOW that in the end, their behavior (which seems somewhat S&M at the time) will make you a kick-butt nurse. be confident.
best of luck in nursing school