At least eight died in the attack, authorities said.
Her husband, Alexander Naessens, learned of Decadt's death less than an hour after the attack when officials at NewYork-Presbyterian Hospital called him, according to the New York Times.
Decadt was the only woman among those killed. She was the mother of a 3-year-old and a 3-month-old, according to the New York Daily News.
“This loss is unbearable and unthinkable,” Naessens told the newspaper. “Anne-Laure ... was a fantastic wife and she was the most beautiful mom to our two sons.”
Decadt's mother and two sisters were not harmed, he said.
The family was still waiting for the remains to be released by U.S. authorities so that they could be repatriated, said Francesco Vanderjeugd, the mayor of Staden, Decadt's hometown in the West Flanders province of Belgium, who said he was friendly with the family.
“A few days ago, I sent an SMS to one of the sisters when I saw on social media that she was in the United States,” Vanderjeugd told the Belga news agency.
“I wished them a great trip, hoping that they would enjoy each other’s company and the Halloween celebrations that are even stronger in America than here. And then it happened.”
He said that another family from the town of 11,000 people had narrowly avoided tragedy in August’s vehicle attack on Barcelona’s Las Ramblas boulevard, saying that terror can strike even the smallest communities.
Vanderjeugd told the Daily News that Decadt was set to leave the United States on Friday.
Belgian foreign minister Didier Reynders, who has been in New York, said three other Belgian citizens were injured in the attack but did not specify if they were related to Decadt.
In remarks with Secretary of State Rex Tillerson, Reynders pledged Belgium's commitment to the fight against terrorism.
“We are in the same coalition against Daesh, we fight to rebuild some countries in the world, but I’m sure that we need also to exchange the best practices to fight against radicalization, homegrown terrorism, homegrown violent extremism,” Reynders said, according to the State Department. “It’s a real fact. We have seen that in London, in Berlin, in Paris and Nice, and also in Belgium, and now again in the U.S.”
After leaving behind a trail of chaos, the driver of the truck was shot and arrested by police, ending what authorities described as a terrorist attack. Officials said the suspected attacker, 29-year-old Sayfullo Saipov, left a note pledging his allegiance to the Islamic State.
New York Gov. Andrew M. Cuomo (D) said Saipov was believed to be a lone wolf who was “radicalized domestically” after moving to the United States from Uzbekistan six years ago.
The others killed in the attack were from the United States and Argentina, said police, who identified the American victims as Darren Drake, 32, of New Milford, N.J., and Nicholas Cleves, 23, of New York.
The Argentine Foreign Ministry identified the five dead Argentine nationals as Hernán Diego Mendoza, Diego Enrique Angelini, Alejandro Damián Pagnucco, Ariel Erlij and Hernán Ferruchi. The New York Police Department said all of the men were 47, except for Erlij, who was 48. (The NYPD identified him as “Ariel Erlis.”)
The men were all longtime friends who had traveled to New York to celebrate the 30th anniversary of their high school graduation.
Birnbaum reported from Barcelona.