In some ways, however, it is like rocket science, in that if you get it wrong, you are going to hear about it.
Sometimes, even if you get it right, you are going to hear about it.
Or worse, not hear about it at all.
In ten years, this book will be one of ten or fifteen books you have written in the last ten years. You will barely remember the plot. You will likely have a lingering fondness for several things about it, most likely the characters and the worldbuilding, and you will have forgotten the rest.
And most of the trauma of the birth.
At this point, it's unlikely to completely destroy your career, even if you bitch it up.
You're probably not going to bitch it up as badly as you think you are.
You are going to bitch up something about it.
The book is better than you think it is.
The book is better than your critics think it is.
The book is worse than your fans think it is.
The book will be as good as you can make it, and bewailing your inadequacies will not make it better.
However, it may make it worse.
This does not have to be that fraught. It will work itself out in the end. The universe is not on fire. In fact, not even the galaxy is on fire.