Look, we didn't part company on the best terms, and that was my fault, I made a fool of myself, and I am sorry, I still don't have thick skin, but I haven't given up either.
I never forgot the "nudges" you gave me to stay the course, and while the path to zen-level patience has been humbling and an even slower than agent and editor wait times on query letters, I'm still on it.
That said, in my humble take of your inquiry, on the points of what isn't working and why it stays with us more than the positive-
It's true that writers (including ME) have to face their weaknesses in the not-so-joyous feedback, and that's why we recoil. But when you consider how bar of excellence leaps higher and competition is fierce for attracting potential agents or editors in our work, the valid nitpicks feel like they're outshining whatever we did right. If they didn't, we might at least get more than ONE non-form rejection once in three years.
I don't have any advice, except that as hokey this might sound to more pragmatic writers, reminding myself that as important as writing query letters, synopses, and everything that requires you to think like an "ad agency" is, it's still NOT the only thing that defines you as a writer. I try to keep that in mind before I get too depressed, sometimes anger wins, but eventually I begin again.

my query letter may "suck" but that doesn't mean the actual book does.
"Writing about a book is just not the same as writing the actual book." That's my personal motto now.
I still take my query letters seriously, but it's OKAY to also tell myself, "Query Letters are important, but they alone don't define all I am as a writer." But when that's all agents or editors see first off, it's hard not to be anal about them, they do matter.
But they still don't define all you are, and just as important, when your query letters or parts of your actual story are critiqued as "less than engaging", if you can honestly say, "This was the best I could do/improve from whatever beta-reader feedback I got" you shouldn't feel shame.
Disappointment? Sure, that's unavoidable, but never shame, but you're tougher than I am in this respect

, or you just don't show your scars as transparently as I do.
