The 22-year-old friends, who both graduated from Bergenfield High School in 2015, were standing outside their crashed car after it hit the divider on westbound Route 80 in Paterson when they were struck and killed by a sedan driven by a Morris County woman, responders said.
Gaviria suggested they set out for a better life together in North Carolina, friends said.
"Sebastian always put others before himself," said Aaron Vaz, his friend of nearly 15 years. "He found out Sabrina was living in her car -- he had no relationship with her -- but he took her in and made sure she had a bed."
Acosta was remembered as a "beautiful soul."
"You made my days at work less stressful and you were the reason i was able to stay calm there," Olivia Borenzo said in a tweet. "You have a beautiful soul and you filled a room with joy, laughs and love."
Nicole Ospina-Barragan said Gaviria will be remembered for his selflessness.
"He was an amazing person with a huge heart that always put others before himself," she said. "He was respectful and caring."
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Oriana Gonzalez, 20, said Gaviria was rarely seen without a smile.
"He had open arms to anyone and everyone, but his smiled stuck onto you the most," she said.
"When you would drop him off home, he would turn around and wave the with that beautiful smile. He made sure you were good.
"You could literally feel how genuine and passionate he was about everything -- his mom, sister, friends and dreams."
Gaviria's Toyota Camry hit the divider near the Madison Avenue overpass just after 11 a.m., responders said.
Moments later, a Hyundai Elantra driven by Leah Kehoe, 34 of Rockaway hit them, NJ State Police Trooper Alejandro Goez said.
A witness said Kehoe went to pass another vehicle and lost control of her car before it struck the couple.
Both ended up on the shoulder of the highway at milepost 59.2 near Exit 58 -- one beneath the Elantra and the other between the two cars.
No charges had been filed as of Monday morning against Kehoe, who was taken to St. Joseph's Regional Medical Center in Paterson with minor injuries, Goez said. An investigation was continuing.
Meanwhile, several thousand dollars had been raised on a GoFundMe for Gaviria and a GoFundMe for Acosta as of Monday.
"He was personable," said longtime friend Darin Diaz of Gaviria. "He lit up the place everywhere he went with that smile. He could be on his last buck but he'd buy you a plate of food and hand a person on the street his last cent."
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