Oh boy. Is this ever difficult. I've led you, up to know, to believe that what you're writing is the pinnacle of literature. That you're bound to write a masterpiece. You're bound to make it big, after all you're a star. Your inner and self critic is going to be whacking you over the head in a very big way. It probably already has, all the way through the process, but now you've got to the stage where you're looking back and you think it's a disaster. "No-one is going to want to read this crap!" You're wrong. I know you're not going to believe me, but you're still wrong. All wrong.
I want to read it, for a start. You got this far, hell, I want to read it. Send it to me, now. Please, I beg you. And I will read it, and I will tell you what I think. And I'm going to love it. I'm going to love that you spent so long working on your story, you've spent so long making it the best it can be - all the way through the process. It's only at the very end that your completely understandable paranoia is leading you to think bad things. Your efforts throughout it all will, I assure you, mean that what you have produced is bound to be very worthy.
Let's be honest, you still might not have written a masterpiece. I don't think you ever led yourself to truly believe that anyway, right? You're maybe not a star, after all. You might not even be a lightbulb, in comparison. But do moths gather round stars? Er, no, except for space moths and I'm not sure they even exist in Douglas Adams' works... but maybe they should. I guess it's important for you to know why you started on this difficult and time-consuming journey. If it was for fame and fortune – ask any writer – "Forget it!" There are a few who make a good few quid/bucks from doing it, naturally. You might not be one of those. What you will get from it is an enormous sense of success. You did something that millions of others have tried and failed. Millions of others got halfway then failed. You didn't fail, no matter what you think.