Choices I see: (let's get this out out of the way first so we can look at more desirable options, okay?) toss it and find another story to tell, Just start out wherever you are now in the story and keep writing until you hit the end. Don't back up, don't rethink, just write it (I know you've heard this before, but one of the problems I see here is that you're second-guessing yourself), put it away for now and write something else. #1 and #3 might be the toughest considering the state of mind you seem to have regarding this story (and God knows I don't want to advise you to do anything that will worsen your headache) but #2 might give you closure, at least for a first draft. No matter which way you go, you might consider writing out a list of things you've learned about writing by taking on this monumental task. Use that list to remind yourself of how far you've come as a wordsmith, then get back on the horse.
I've decided to scrap my original idea. But fortunately, a new one came to me just last night. I shared it with my husband, who was actually quite enthusiastic about it. He normally hates all of my ideas. lol We disagree on a few things, but he likes the general premise. So maybe ditching the plot and not thinking about it was a blessing in disguise!
