You're the author, and you're in control of the story. If you want to keep writing, I think you can make it happen. If you want to be done, you have the power to make that choice too. It's up to you to weigh the pros and cons and decide whether your manuscript is worth your precious time.
There's a lot of writer advice out there that errs on the side of keeping it up at all costs. "You can work through anything!" "Never quit!" "Think of how good it will feel when you actually finish this manuscript!" Well, I'm here to say that not all manuscripts are meant to be finished. And some of them should be quit.