extremely disappointed and sad
crestfallen - dejected
If you are ‘crestfallen’ then you are in very low spirits, usually as the result of a crushing disappointment or having failed unexpectedly. It implies a dark and depressing feeling that can be all-consuming, but is usually only temporary. That is because being crestfallen isn’t innate, it is a reaction to a particularly negative result or situation.
I was absolutely crestfallen when I heard the news. I felt sure that I had done enough in the interview to get that job.
After that lucrative deal fell through at the last minute, it was hard to raise morale in the office. Everybody was just so crestfallen.
Chris obviously didn’t have any inkling Jenny would betray us like that. He looked as crestfallen as I did.