I'm sorry to hear that you're experiencing such difficulties. I agree with the post above...there are other ways to get into a university nursing program. It might be a few extra steps and some money, but there is no straight path to get to your destination. It also doesn't matter how long it takes you to get there, but as long as you finish.
It can be tough and discouraging, but you came this far. Maybe you're learning style has changed and or you're not incorporating things into your schedule in order to help you get the grades you know that you're capable of achieving.
Speaking from experience, I struggled in elementary school math and had awful math teachers. I barely passed grade 9 math and then excelled with flying colours in the applied grade 10 math - I took mixed level math in grade 11 and did well. However, I gave myself some time after graduation and I ended up doing well in college math.
Now, I have a completely different perspective on math and I actually enjoy it. The important thing is to weigh your options and explore your other avenues. Sometimes things don't work right now, but that doesn't mean it won't work later.
Hope this helps