Who would let me be a nurse?

I am now officially in the RN nursing program. I never dreamed the bar would be set so high to get into what is really a technical school program. I have slaved over all of the prereq classes, sweated out the entrance test (TEAS), and was finally told I'm in. Now I have to think about the stuff I have been avoiding by running on the little hamster wheel for the past year. WTF was I thinking? I've never worked or even been close to anything like healthcare, and while I don't think the guts, gore, poop, vomit, whatever are going to deter me, the fear that I am going to screw up in a massive way is terrifying me. I mean, I do stupid crap all of the time in my regular life. My attention span is about the same as a gnat. Also, I've heard the classwork is so much harder than anatomy, chemistry, algebra and so on. How much harder? Am I stressing for nothing? I mean, it's not like I'm going to do brain surgery.