The unhinged mother who drove her minivan off a Newburgh dock and into the Hudson River told her four children that she wasn't leaving this world alone.

"If I'm going to die, you're going to die with me," Lashanda Armstrong told the children before the vehicle sank to the bottom of the river just before 8 p.m. on Tuesday, the only surviving child told authorities.

Armstrong's 10-year-old son, Lashaun, escaped the doomed family minivan - opening a power window and swimming to safety in the two minutes it took for the vehicle to sink.

But as he wriggled out of the window, his mother snatched his pants leg. "I made a mistake," she said before finally releasing the boy, the child told authorities.

After swimming to shore, the dripping-wet Lashaun made it to the road, where he was picked up by Meave Ryan, a good Samaritan who took the boy to a nearby firehouse.

"He was waving his hands, screaming 'Help me!'" said Ryan, 31. "He said, 'My mommy just drove the car into the water.'"

Shivering and barely able to speak, little Lashaun told firefighters how his mother had launched the van into the river with his siblings inside and how, just moments before, she dialed her dad for help, the kids screaming in the background.

"I'm sorry, I'm going to do something crazy," Armstrong said, according to the boy's story.

That prompted a 911 call that brought police to her Newburgh home, but it was too late.

Police wouldn't confirm details of the domestic dispute that preceded the murder-suicide inside the tan van, but neighbors said Armstrong and longtime boyfriend Jean Pierre were frequent fighters in their second-floor home.

Armstrong, who battled with Pierre over his womanizing, had twice asked to get the apartment locks changed in a six-month period - most recently in March, the building landlord said.

Pierre - nicknamed "Prime" - was the father of the three dead children. He began dating Armstrong, 25, when they were in high school.

"They went to the prom together, put it that way," said the dead woman's aunt, Angie Gilliam, who made the futile 911 call.

It was unclear if Pierre, 26, was at the apartment before Armstrong's inexplicable death ride - a six-block drive from her home to a concrete boat ramp and into the river.

A 22-year-old neighbor said she and Pierre had a three-month affair while Armstrong was pregnant last year with her last child, 11-month-old Lainaina.

The baby, along with her brothers Landon, 5, and Lance, 2, died with their mother.

Armstrong knew about Pierre's roaming eye, and it became an ongoing argument.

"There was nonstop arguing late at night - normal kind of stuff," said the neighbor, who later befriended Armstrong. "Why are you back so late? Who were you with? But I can't picture her putting the kids in the car and doing that."

Cops released Pierre on Wednesday night after a day of questioning. He is not expected to be charged.

Christine Santos, a family friend of Lashanda Armstrong, takes a moment in front of the family's home. (Groll/AP)

Weeping members of the Armstrong family released three star-shaped white balloons on Wednesday at the boat ramp where the van lurched into the 45-degree river.

They lit candles and left flowers, along with three stuffed animals for the lost children: An elephant, a monkey and a dog. Relatives retrieved clothes from the family apartment for 10-year-old Lashaun. "My nephew's doing fine," Gilliam told reporters. "He's really not talking."

An hour-long search turned up the sunken van, holding the four bodies, about 75 feet offshore in 8 feet of water.

Shortly before Lashaun reached the firehouse, Gilliam called police about the domestic dispute. They arrived to find the apartment empty; Gilliam arrived a short time later to word of the deaths.

"We're doing the best we can," she said.

 

With Daniel Beekman

lmcshane@nydailynews.com