You are not alone. I'm actually in a similar position as you right now. I too did well in high school. Got to college "lacked off" and pulled myself together toward the end, with a decent GPA, but I could have definitely done MUCH better.
I'm also applying to CC-Nursing programs and im very anxious about it too.
just to give you a bit of hope and a stress reliever, a couple of schools I'm looking into do not look at the cumulative GPA but are focusing more on the pre-req courses and the grades/GPA in those classes. So dont worry too much, as you still have a great chance at making a good impression, at least GPA-wise! Soooo good luck and do well in those pre-req courses!!!
And thanks for posting this! I can totally benefit from responses to this post as well.