Annoyance is the first thing.
Then comes denial. No! It's fine! A few tweaks here and there will sort it out. Just write the sex scene - you can do those in your sleep - and don't worry if it doesn't totally gel.
Then there is acceptance and an odd sense of relief because you know that in the long run this is the right thing to do.
A stiff drink before dinner and calmness comes. As does the new structure. I sit in the kitchen and watch the food get prepared (lucky old me to have someone who can cook!) and I scribble it all down in a note pad.
There it's finished!
Or at least the new structure is complete with my characters clearly defined on paper and in my head. Now all I have to do is type the thing out. Thank goodness we live in an age that has the wonders of Word Processing, otherwise this could have been a real pain in the butt.
It means the book will be out later than planned, but don't worry.
Keep calm, and say 'Thank You, Jack!'
Thank you for making the effort to turn it around, and not churn out a load of old tosh!