rebellion?
Some twelve-letter words meaning 'express/expressing strong feelings' include: Distractedly Hysterically Passionately Unrestrained Uncontrolled
Possibly Complaint, or, Challenge.. both of these appear to meet the criteria you had. Good Luck :)
objection
The word 'protest' is both a noun (protest, protests) and a verb (protest, protests, protesting, protested).The noun 'protest' is a singular, common, abstract noun; a word for a statement or action expressing disapproval of or objection; a word for a thing.The noun forms of the verb to protest are protester, protestation, Protestant, and the gerund, protesting.
A strong reaction or expression to human actions
a strong desire to achieve success
yenned
fort
yearned
Lust
Yen...that crossword stumped me to...
The opposite of vindicate is condemn or censure, meaning to disapprove or express strong disapproval or criticism of someone or something.