I'd tell her to buzz off!
Sooooo many different kinds of people are nurses...and soooo many different kinds of people go into nursing school. I had absolutely no experience when I got accepted into a BSN program, and I took one of the semesters during the summer, which I guess could be considered accelerated. It was hard, but it was hard for everybody. It's not so much that it's hard, but it's time consuming. If you're not horrible at taking tests, and you study, and actually listen to most of the content in class, you should be fine.
It is weird to think of someone you know being a nurse, because nursing requires the kind of nurturing attitude that you don't see everyday in your friends. A lot of people said they couldn't see me as a nurse, because I'm not the "super-friendly, mothering" type, and I doubted myself, too. Somewhere in the third semester clinicals was when I really started feeling like I was actually doing something beneficial for the patients, and I developed an ability to deal with people in their various vulnerable conditions.
Nursing is different than other areas of education. It can take some getting used to. I think there were 6 guys in my graduating class of 40-something.
Oh yeah...learning to ignore her is just the beginning. There will be many more stupid things said by teachers and hospital staff that you'll have to learn to ignore.