"much disappointed" is a correct and usable phrase in written English.
It can be used in situations where someone is very disappointed. Example: "After studying all night for the exam, I was much disappointed to see that I had failed it."
We were much disappointed in Virginia generally on the day of the great eclipse, which proved to be cloudy.
The merits of L'Éducation sentimentale, which appeared a few months before the outbreak of the Franco-German War of 1870, were not appreciated, and Flaubert was much disappointed.
When Mario Da Rugna heard that Switzerland had voted to curb "mass migration", he was not so much disappointed as horrified.
"But like many other young leftists I've been very much disappointed by the Italian mainstream left over the past 15 to 20 years.
Citizens who may have harbored the idea that there was a murderously efficient J. Edgar Hoover of the Internet, working day and night, will be much disappointed at the contents of two recent government reports.
These were emphatically not the songs of a swain disappointed in love, but those of a man disappointed by life -- or not so much disappointed as confirmed in his low expectations.
"What hurts most . . . is that I know how much I disappointed my wife," he went on.
Mr. Levitt is repeatedly described as a demanding boss who reprimanded employees by telling them how much they disappointed him.
They lost so badly, in other words, that coming out of the half — down twenty-four, thentirere team outscored to that point by the Mavericks' sharp-shooting bench — the report from the Lakers' locker room ("No one got up and made an impassioned speech") couldn't surprise, however much it disappointed.
The downside of that type of differentiation plan is that a customer service bungle hits you harder than it would another airline, since travelers with high expectations are that much more disappointed when their experience doesn't go well.
Imagine how much more disappointed the person who sees you naked will be then.
