Oh God, Chibi, I’m so sorry! How very Miranda Priestley of her. I hope things work out soon with HR or the agency.
Imposter syndrome is the worst, and it doesn’t go away, in my experience. I have this huge problem where whenever I hear something nice about my work, even from a total stranger, my brain instantly dismisses it as “They’re just saying what I want to hear.” Whereas any negative review has a serious effect on my whole view of my writing. (“This anonymous reviewer says I can’t write characters, while this other anonymous reviewer loves my characters. Well, obvs the first one must be right. Characters are my weakness.”) It’s a horrible habit that I think comes from the human tendency to be more alert to negative stimuli because they might be threats —i.e., caveman brain. And it’s good to take in critique and strive to improve, for sure, but you need to pay attention to the kudos, too. The best solution for me is to stay off my Goodreads page.