Hello OP, and congratulations on your promotion and the extra pay. Well done on getting through a tough week.
I've not read all the responses, but I have read all your posts.
You took the job last year and we're now in October. How many terrible weeks have there been versus satisfying ones? Are the terrible ones becoming more sparsely distributed? Are you getting better at managing the tough deadlines and the different demands in this role? Do you enjoy the different challenges and value the skills you're learning - or could you, with a bit of breathing space around the deadlines and the pressure?
Could you get a career coach/mentor to help you reflect on these practical questions? It may be you arrive at the conclusion that this job is just one job in a long career, that you have learned x, y, z from it, and it's time to move on to a different role.
The family/school script about being 'the clever one' is not helping you, is it? Time to ditch it. Unless you're in line for a Nobel prize, most of us don't do 'great things', do we? The difference between a job earning £80k and £120k (or whatever differential you think has an impact) doesn't really count as 'greatness' in the grand scheme of things. It's fine to be ordinary. As you're discovering, 'ordinary' has plenty of challenges of its own.
I'd take the rather romanticised responses about children not remembering or caring about the material things with a pinch of salt. Children do notice scarcity or tension around money, and all the popcorn and hot chocolate on the sofa together won't necessarily blot out never going on holiday or having cool clothes or money for hobbies.
FWIW, I gave up full-time work about 8 years ago, and my income dropped to a third of what it had been. But the extra time I had meant I could explore what I really liked doing (turned out that was learning languages, taking exams in them, writing a blog, learning lots of DIY and gardening skills and getting fit - all relatively inexpensive compared to how I lived before) and budget really smart. So I have made less money go very much further and now even save more than when I was working FT. Not saying this would translate to your circumstances, but it is possible to maintain an interesting life on less money.