A cruel series of catastrophes — including job loss, illnesses and eviction — has left a once-six-figure-salaried sales exec homeless and living in his car with his wife and their autistic and brain-damaged adult son.

“We don’t want to wind up in a shelter,” Stewart Scheyd, 59, told The Post of struggling through the upstate winter with his wife, Denise, and Sky, 20, their youngest child.

“Because they would separate us and who knows what would happen to a kid like Sky.”

The Scheyd family has been living in their 2002 Ford Taurus since June, when they were evicted from their rental home in Monroe in Orange County. But their troubles go back decades.

All three of their children have suffered serious illnesses.

Sky was born severely autistic.

Their oldest son, Freedom, now 25, was born partially deaf and missing his left ear, and their daughter, Ocean, now 22, fought leukemia at age 12.

At around the time Ocean struggled with cancer, the recession struck; Stewart Scheyd lost his high-paying job as a telecommunications engineer.

The family tightened their belts and weathered each successive storm. Both Stewart and Denise took lesser-paying jobs to spend time with the kids.

Then, three years ago, when they were still living in Monroe, Sky, already low-functioning, began acting psychotic.

There were screaming fits, obsessive-compulsive behaviors. It could take three people to restrain him when he had an outburst.

“The doctors were saying he was crazy,” said Denise, who has home-schooled Sky since he was 12.

She knew something else was at play with the then-17-year-old.

“His eyes would dilate and he’d start screaming and every day it got worse,” Denise said.

Denise suspected Sky might have autoimmune encephalitis, a rare condition in which the body’s immune system attacks healthy brain cells, causing inflammation in the brain.

Doctors confirmed the diagnosis, and Sky began intravenous therapies that continue to this day.

He is starting to verbalize again, the Scheyds say, and no longer needs both his parents to be with him at all times. Denise was able to take a part-time job as a school bus matron.

But she earns just $1,100 a month, not enough to secure the threesome a home.

The three spend some nights at their older kids’ apartments, but that’s a squeeze. Both kids have roommates of their own.

Friends, too, have helped where they can, including subsidizing the Schyeds’ stays at The Stony Point Center, an interfaith facility that provides temporary lodging. They’re also on a long waiting list for subsidized housing.

But when all else fails, only the car remains, at least for as long as they can still afford gas and repairs.

“It’s like being in a battle and I’m leading this troop but I have no idea where I’m going,” Stewart said. “I just have to keep moving forward. I want a home for Sky.”

The family has set up a GoFundMe page in hope of donations.