Sorry, just a student here. Still, my advice would be to talk to the place where you see yourself eventually working as a NNP. Find out what they would prefer. If your heart is really set on one place, do what you need to do to get in there. If they don't care either way, then go with your heart. This may help you to rule out one or the other.
In reality, 45K seems like a lot of debt, but it's not really, not when it comes to an education. Figure up your salary now and the salary you will make as a NNP, find the difference and then figure out how long it would take you to pay back that 45K, it may not be as long as you think. Imagine it this way . . . can you survive on what you are making now? If you can and you are ok with this, plan on spending whatever you need to on schooling and then put the difference of your new salary and your old salary back into the student loans as soon as you graduate. For example, if as a NNP you make $1000 more a month (sorry, I haven't looked into this part of it, so not sure if that is realistic or not, but if not, plug in appropriate number) put $1000 a month into student loans, then you would only have 45 months of loans to pay back (less than 4 years). Your standard of living will not change and then, once you are debt free, you will have extra money each month.
I know it is a hard decision, creating debt always is. Follow your heart and best of luck to you in making your decision. Whatever you choose, don't look back and don't regret it because either way is a path to what you ultimately want to have and both of them will get you there.
Good luck & keep us posted as to what you decide to do.