If you have so many doubts, why did you even apply for nursing school
? What made you decide to study nursing? Why don't you start from there.
No pig disection is waiting for you, but you will encounter all kinds of things that may gross you out. Not only that, you have to read and read and read in nursing school. I'm not kidding and don't mean to scare you, but it's true!! You will probably find that out in the first semester/quarter.
Without a strong commitment you may easily give it up. Better not to start than to quit after you spend so much time? Well, I can't answer that for you. Talk to your nursing student advisor even before you start. S/he may help you to have a bigger picture of what's like to be a nurse.
English is not my primary language (I'm from Japan!) It was so difficult for me to go through the nursing school and get a BSN degree. But, it was worth of my effort. There are so many things that you can learn and contribute as an RN. Good luck to you.