It's a happy time, and a difficult time, when the things you've written all turn to garbage. It means that you have leveled up. You see now what your critics has been talking about and it is time for you to become better. You are not yet there, though. You see your flaws but you don't know how to fix them. You need to accept that what you were was nothing more than a stepping stone and you'll have to power your way through your garbage pile again to make it better. Because of this, it is also a sad time. All your efforts seem wasted. All the carefully crafted sentences that you made with the best of your abilities seem pointless when they'll soon be changed to something better. But what is most difficult to swallow is the realisation that your book is further away from a finished product than you realised. Making you wonder if you will ever catch up to your own worst critic - if it will ever be good enough to publish. (Sorry. I just needed to vent my own frustration)
I accidentally read a couple paragraphs of my own work a few weeks ago without knowing it was mine (it was loaded on an old Kindle I hadn't used in a while and I just picked it up and started reading on whatever page was open) and liked it, and I was so relieved when I realized what had happened! Because I agree, too often "fresh eyes" are good mostly for pointing out what crap everything you wrote was...
Completely understand you and I think all writers feel like this from time to time. It comes in waves; sometimes you're pleased with your work and other times it's just garbage to you. But I think that's a good thing, then at least you know that you have something to improve on. It would be bad if you think your writings were perfect. And, it's not time or effort wasted, it's a part of the learning process (and a crucial one). You might not know how to fix your faults now (I don't either) but as long as you keep on doing what you're doing you will little by little be better and be able to achieve, maybe not to be a bestselling author, but be satisfied with your work. Being published is one thing, but being able to enjoy, and sometimes like, what you're writing is more important, I believe. Well, you know all this. Keep writing and don't forget why you like it so much.
Experienced this very recently, and yes, it's almost soul crushing. What got to me the most was if I would ever truly understand how to correct my mistakes, learn from them, and actually find a better way to write through the criticism I was getting. I was told that I was "telling" instead of "showing" the reader...like, wtf does that mean? I get what they were trying to say, but how in the hell do I go about doing it if I wasn't already doing so? After stewing on this a couple days, something clicked, then I went back to the work in question and then I understood. I am now actually rewriting the entire thing, over 7,500 words, and it's improved greatly IMO. I learned that starting over and writing something from scratch that you just wrote is extremely helpful. You stop worrying so much that your work is wasted, and instead realize that now you just have a really great outline for the story you want to tell.
