A 40 year old should not be this confused help!

Where do I even begin? I'm a first semester nursing student, going part-time (doing Nursing Skills and clinicals this semester, done with Pharm and Fundamentals). I have been questioning my decision about nursing practically since the day I begin school. I have been a "sheltered, living in my safe little world" stay at home mom for pretty much my whole adult life. 3 years ago I decided to go back to school because our boys are growing up (oldest is 22, youngest is 15) and I felt I needed to do something. Decided on nursing for many reasons: I love people, can't see myself sitting behind a desk, I have been a caregiver in one form or another pretty much my whole life, will be able to get a job that pays enough to support me in case something happens to my husband, people that know me say I would make a great nurse because I have experienced some tragedies in my own life so I can really relate to people who are suffering.

School so far has gone very well for me, get good grades, jumped through all the hoops to get into the nursing program itself and here I am really not knowing if I should continue. I have been stretched to the limit and I know this is just the very beginning, the "best" is yet to come. I am very hard on myself, pretty much internalize everything and I ask myself almost daily, "What will it be like when I actually become a nurse?". I have been reading forum after forum of how stressful the job of a nurse is and it scares me. The thing that probably scares me most is that I will make a mistake and end up hurting someone. Is it normal to constantly question my decision to go into nursing or is it a sign I'm going in the wrong direction? I also have been asking, "Do I want to be a nurse, or do I want to be happy?". Is it even possible to be a happy nurse???

I guess the beauty of getting older is getting to really know who you are as a person, seeing your own limits, I really wonder if my "overly worried" personality will just destroy me as a person? I sometimes think it will just wipe me out completely and I will have nothing left. I'm not this happy-go-lucky type (wish I was), instead I take the world on my shoulders and carry it. I can't even imagine how heavy that weight will be as a nurse. All I keep hearing from friends is: you'll make a great nurse, you can do it, you're so smart it would be a shame for you to quit now, etc, etc. I want some real answers, from people that are doing it. Your honest advice will be so greatly appreciated!