The word 'fateful' is correct and usable in written English.
You can use it when referring to something having significant consequences in the future. For example: "The decision was fateful, as it ultimately determined the future of the company."
The first, and most fateful, chapter began in January 2013, when – unable to resist backbench pressure any longer – a mid-term prime minister who hadn't won a majority conceded a referendum on whether Britain should get out of Europe.
Since then there's been little more than speculation, conspiracy theories and titbits of tangible information about what really happened that fateful spring morning, when MH370 disappeared with all 239 people on board.
Any discussion of floods in Mumbai begins with a ritual invocation of one fateful date: 26 July 2005.
Benita Johnson said she spent more than 24 hours with her hand chained to the wall through a metal eyebolt, starting in the pre-dawn hours of April 15 , 1995 listening to Zuley tell her she had a fateful choice to make.
More fateful restlessness soon showed across a broader canvas.
"You don't have to look too far from this magnificent hall to find children still living in poverty or trapped in failing schools," Clinton said, before referencing the fateful night when Martin went out to buy candy and an iced tea.
There are also those fateful days in 1954 when Werner Bischof and Capa were found to have been killed.
Day 6 London The fateful last day is here.
Shortly after those fateful 21 minutes, Clinton's team sent a nine-page memo to reporters "about an understandably confusing situation", which attempted to clarify the contradiction: "Secretary Clinton chose not to keep her private, personal emails that were not federal records," the statement from her office said.
Her fateful encounter with a killer whale in Jacques Audiard's Rust & Bone made a splash here last year but didn't, in the end, bring home the awards bacon.
When Turkey goes to the polls on Sunday, in what is shaping up to be an epic and fateful election, Erdoğan and his legacy will be the main, if not the only, issue on voters' minds.
