I so went through that feeling (many times over) and I had already fled the USA back to my "beautiful Sussex" 8 years before....but in between that time the UK had *already* really changed and I truly began to hate it - although to be honest a lot of that is to do with the people- I think a lot of English people have severe communication & personality problems that they are unable to overcome due to how Brits live, work and are intertwined so closely - over here you can just isolate yourself a little more thanks to the car culture, more space, huge stores and people don't tend to be "in your face" all the time.
Anyway, I digress! For my medical I had to go to Edinburgh and we both totally fell in love with it and although we knew it would be prohibitively expensive to live there, we were upset we'd spent many unhappy years in the beautiful (but overcrowded & expensive South East) and that maybe we should re-think the whole move. However, my gut instinct was that the UK is only so beautiful if you have the funds, personality and general wherewithall to enjoy it. Eg; we didn't have a car, so were limited to trains/buses..........our salaries were simply not enough to buy us anything larger than a one bedroomed flat in the towns (when my dream is rural, tons of trees, grass, fields etc) and so on. But like you, I woke up and thought Sussex is just so beautiful in the spring and summer, my laundry was out on the line....we had money to enjoy it etc (but only because we'd been saving for a year and a half solid, Edinburgh was a mini-vacation (and horrendously expensive for 3 days) and we knew we'd be leaving soon.
Deep down in my gut, I just knew I'd have far more chance of achieving the rural lifestyle I craved and heck, might even get a job I like......I was really down on my local Gov job in the UK, being treated like an idiot one minute and yet carrying the workload of 4 people the next and with no chance for advancement either laterally or otherwise, thanks to the "face doesn't fit" policy and politics of civil service.
You all know now how it turned out....we couldn't be happier! His job came first (it came via an old friend from here, but if he wasn't capable of it, he couldn't sustain it), my job came a month later.......I almost didn't go because I felt it would be way too overwhelming for me.......here I am 3 mths later and finally we got our new house (rented, but it's such a step up from the tiny apartment we moved into to save up to come here), yes, we had to stay with in-laws for this long (but now I have a wonderful reason not to see them!)Yes, a lot of things fell into place for us, but I don't let people just say "oh you got lucky", because we planned, saved, prepared to be able to come and take advantage of any opportunities that might come our way and when they did, we went for them, so I won't have it that it's all luck, but I do think timing and your frame of mind count a lot.
What will not happen for people (and I am eternally surprised when they think it will) is think that all their problems will magically disappear when they leave somewhere they dislike......it's not that simple, but it really can help.
Finally, what helped me was knowing in the back of my mind that I could indeed always come back, BUT making the decision in my head that I absolutely had to make it work and would NEVER be coming back - that gave a finality to the decision and the drive to actually make America my choice and my home with no back-up....this strategy actually helped with the to-ing & fro-ing of where to settle for good. I believe too much choice can actually be a bad thing in life and a large part of why some anglo-american couples don't settle because you have the choice of many countries and it's SO hard to settle on one place! Other people like the security of knowing they can return, but that didn't work for me.
Hope the nightmares are better, that's definitely stressing you out more than it should * hugs*