Well, just to provide an update, these past few days were pure unadulterated emotional whiplash. The issue got resolved although it didn't placate the client, so I've been having post-mortem meetings, Teams calls, chats and e-mails with a whole lot of people including our CTO (whose language has reached one f-word per second at some point) and a pair of internal reviewers, and I've been told mixed messages to the point where I didn't just not know if I'm off the hook, I couldn't even be sure if anything was actually blamed on me to begin with. The internal reviewer told me that both the client and the CTO have blown this incident out of proportion, it would've happened anyway without me making a mistake, and it's primarily the process that needs to be fixed, while the CTO had attached an e-mail chain to the invite to the post-mortem meeting in which they singled out my delay in triggering the update as the sole root cause of everything that happened. Luckily, they didn't attend the meeting that just ended half an hour ago, but it still felt like I was being court-martialed, with one executive flat-out demanding that I clarify if I had simply made an error in judgment or actually straight-up forgot to do my job, while our department head played the role of the good cop and kept reassuring that we were looking for ways to improve the process, not to point fingers.
I guess as no one told me there would be personal consequences for me, I should feel relieved, but I still can't believe this is over. I just hope I can finally get a proper good night's sleep after all this stress, I almost feel like I aged a decade over these four days.