It sounds like you made the right decision to get the problem fixed asap, however I do feel that they may have charged a pretty high amount. I don't know how charges work in your area it may just cost more where you live vs where I live. I had my dog in the emergency vet 3 days and it did not cost over 3,500. She had 3-4 blood and one plasma transfusion as well as tons of other testing and an autopsy done. I do believe they do need to charge more to have vets in the office 24hrs a day and support the testing etc. Your costs seem very expensive compared to my 3 day nightmare. It could just be a cost of living difference between your town and mine.
I wouldn't feel bad paying the money though its a life your saving. I would not have taken any risks either, best to fix the problem early she could have had unforseen complications.
Pretty rotten that they wanted to up-the surgery with the bloat thing, thats just wrong