Low morale

I've just finished writing a book in a month. It was great, I was running on adrenaline and my brain was boiling.
Now the book has gone into academic proofreading.
I'm releasing it next week.
But, every time I finish an important deadline, I have a kind of moral dip, a mini-depression that lasts a day or two or more, and always ends with "damn, these idiots are pissing me off, I can't see their faces anymore".
Does this happen to you too?

Yes, of course it has happened to me and I am sure that to many of us. These things happen due to insecurities of ourselves, you already set out to write a book ( my congratulations, we don't all have that ability), the book is already written and waiting for its release, right? Bro, positive mind always, we can't let a mistake hinder our way, we learn from the error and move on, good luck, positive mind always bro!

In fact, it was a subject I'd had in mind for a while, so it's almost as if the manuscript wrote itself.
Well, the truth is, I did do some investigating and interviewing.
I asked an acquaintance to proofread a specific chapter, because I had a doubt.
So he offered to proofread the final version before I put it on sale.
I'm waiting for him to come back now.
It's just that... going back to the daily grind, like today, really demoralizes me.
The good thing about writing this book was that I didn't have time to think about anything else.
And now I'm thinking again.