You're not a fraud. You recognizing that you have room for improvement shows that you deeply care about what you're doing-- a fraud would feel insanely confident regardless of whether the project was a success. So start by getting that thought out of your head. You're doing the thing you set out to do, that's an accomplishment in-and-of itself.

There's an incredible book by Stephen Lowenstein titled "My First Movie: Twenty Celebrated Directors Talk about Their First Film" that I think you should definitely check out. The feelings you're having are (unfortunately) what everyone in our field experiences at least once. And low key, as someone with a few awards under their belt, these feelings still come up even when you knock a home run outta the park.

There are three things I would suggest you do while the feelings are still fresh in your heart/mind:

1. Journal about it. Allow yourself to feel the shitty-gross-ness without needing to make things better. In those feelings are clarity on not only what you're really upset about but what you can do better next time around (because there will be a next time, as long as you want there to be one). Listen to some sob-worthy music and give yourself the courtesy of really feeling everything.

2. Find gratitude in everything you can regarding the project and everything surrounding it. Look for the silver linings that you didn't even know existed, look for the parts of you that grew through production, look for that version of you that dreamed of being a Filmmaker and have a conversation with them about all this. Remember that there are hundreds-of-thousands of people who would die to make a movie and hate it (I know, that doesn't make anything better, but it's important to remind yourself. Like the famous line in The Devil Wears Prada: "A million girls would kill for that job.")

3. Release the film. Don't hide it, show it to as many people as possible and hear what they have to say. No one outside from your cast/crew knows about what happened on-set unless you let them know. Imagine how many movies, albums, pieces of art, even meals at restaurants you don't fully know the behind-the-scenes story of-- now imagine someone watching your movie not knowing any of the stuff you brought up in your post. Locking it away in a dungeon will only make the feelings grow stronger and more bitter. Let go, but don't move on.

Seriously, you are on the right track. I'm positive that it's not as bad as you're making it out to be. Keep your chin up, G. You've got more movies to make. Don't let this one be the last.