“I was in an explosion that ran over a double stacked antitank mine and pretty much destroyed the Hummer behind us, blew ours up pretty good,” he said. “Suffered some pretty substantial injuries. . . . So I spent several years going through many surgeries.”

He told the interviewer about the post-traumatic stress that followed, along with the divorce. Mounting debt forced him to live in his car, which was almost repossessed. He used meth, he said, and “did a lot of time drinking.”

“I was in the worst way,” he said, his eyes hidden behind sunglasses because, he claimed, the sun aggravated his PTSD.

People who heard the story rushed to help. Blackstone got counseling from a veterans’ assistance group – and support to launch one of his own. A charity gave him a mortgage-free home valued at $150,000.

And on that spring day in 2013, the story got Blackstone onto British public-service television, to talk about the hidden wounds of war.

Only, his war story wasn’t his own.

He had stolen most of the details from another Marine’s real, true ordeal.

Prosecutors say Blackstone co-opted the story of Casey Owens, a Marine corporal from Houston who actually endured much of the suffering Blackstone described.

Owens shot himself in the head in 2014, a decade after the antitank mine explosion that took his legs and damaged his brain. He is buried at Arlington National Cemetery.

Blackstone, who used details of the dead Marine’s story for profit, even while Owens was still alive, is likely headed to prison after pleading guilty to stealing valor.

His lie was exposed after he told “his” story to someone who knew it equally as well – a Marine who was there the day Owens nearly died.

Owens and Blackstone were both swept up in the wave of patriotism that followed the 9-11 attacks, according to the Dallas Morning News. Both were Texans who joined the Marines. Both were deployed to Iraq in 2004.

Blackstone’s deployment was curtailed by appendicitis, and he was sent back to the United States, according to the Morning News. But during his month in Iraq, he learned of the explosion that nearly killed Owens.

During a rescue mission, a mine had blown up his Humvee – 80 pounds of explosives going off under his passenger seat.

“It blew him out of the vehicle and blew off his right leg above the knee and mangled his left leg and then broke everything else under the sun,” his sister, Lezleigh Owens Kleibrink, told The Washington Post. “A piece of the carburetor had gone close to the carotid artery in his neck.

“He was just a broken mess.”

Owens nearly died. His family made the decision to have his shattered, surviving leg amputated to save his life.

Back home, he received a Purple Heart. He posed for pictures with President George W. Bush. He testified on Capitol Hill about the Department of Veterans Affairs and how “those, like me, who were paid as a Marine Corps grunt to do their job to the best of their ability never questioned whether if we got injured my government would be there for me.”

Owens, a former high school football player, took up new sports, gliding down the mountains of Aspen on a monoski. He competed in the Vancouver Paralympics and sped through the 2005 Marine Corps Marathon course in a hand-cranked wheelchair.

To help him cope with PTSD, he got a service dog.

But the headaches never left. He drank to battle persistent depression and pleaded guilty in 2010 to drunken driving, according to CBS News. His amputated legs wouldn’t heal properly, thwarting his efforts to walk on prostheses. He tried college but was hampered by his brain injury.

“I really don’t think I’ll ever be free,” he told CBS in 2012. “I don’t think the burden of war is ever gone.”

After returning from Iraq, Owens never slept a full night, his sister said, because his mind always returned to the horrors of war.

When her brother killed himself, she was devastated, but not surprised.

“He just started to become hopeless and felt that things were not going to get better,” she said.

Blackstone first told his bogus story to federal officials in 2006, when he tried to get VA benefits, court documents say.

His application “falsely claimed that, while deployed to Iraq, his Humvee vehicle struck an antitank mine and he sustained multiple blast injuries,” the documents allege. Months later, he told a medical examiner that he had “lacerations and physical injuries as a result of the explosion.”

To back up his story, he forged two witness statements, prosecutors say.

The Department of Veterans Affairs started paying him monthly disability benefits in late 2006.

In 2012, Blackstone submitted an application to the Military Warrior Support Foundation, which gives mortgage-free homes to wounded veterans. In the application, he said he had been awarded a Purple Heart.

In sharing his story, Blackstone frequently showed two pictures to people – one of a mangled Humvee, and one of Cpl. Casey Owens in a wheelchair, saluting. He told anybody who would listen that he was in the convoy when the mine exploded – and that he had saved Owens.

And then he told the story to Jerome Smith at a retreat to help heal “the invisible wounds of war.”

Smith was in the Humvee behind Owens at the time of the explosion. He was witness to the carnage – and the aftermath: For years afterward, Owens called Smith, sounding increasingly depressed.

Smith went to a week-long Focus Marines retreat in St. Louis, to see if it might help his own healing. One of the first people he met was Blackstone, a Focus Marines mentor.

The two men had served in the same unit, the 1st Battalion 7th Marines. They swapped stories over a fire, and Blackstone told his familiar tale about the mine explosion that nearly killed Owens.

He told Smith he was hit in the forehead by shrapnel and that he then grabbed a fire extinguisher and ran, “putting out the fire on Casey’s body.”

“He brought up Casey in a way that made me really uncomfortable,” Smith told The Post. “That was the first red flag. He busts out a picture on his cellphone of the damaged Humvee. And he busts out a picture of Casey Owens sitting in a wheelchair saluting in his dress blues.

“He had no f–ing idea that I was Casey’s buddy.”

At first, Smith tried to give him the benefit of the doubt. Smith admits he doesn’t remember everything perfectly about the explosion. But the more Blackstone talked, the more skeptical Smith became.

“I started asking him people’s names,” Smith said. “I started asking him about specific events. I asked him about specific days.”

By the end of the retreat, Smith felt strongly that Blackstone had inserted himself into Owens’s war story – turning himself into a hero even though he was nowhere near the blast and never in danger.

Smith just had to prove it.

After leaving the Marines, Blackstone built a new life for himself. He had the mortgage-free house and a fiancee. Following the lead of Focus Marines, he started his own organization to raise funds for veterans.

But Smith and others from the 1st Battalion 7th Marines began working to expose Blackstone.

They started a private Facebook group that dissected Blackstone’s story. They found the Marine whose name was at the bottom of a letter detailing Blackstone’s injuries, and that Marine denied ever writing it.

Their mission took on new urgency after Owens’ suicide.

“You’ve got Casey, the man who’s paid the ultimate price after he struggled to get the help he needs, and you’ve got this guy over here fraudulently claiming the same story and receiving every benefit and even some above and beyond,” Smith said.

An email was sent to Focus Marines, saying Blackstone’s testimonial on the foundation’s website was a work of fiction. Someone else called the feds.

Blackstone was arrested Sept. 15. He pleaded guilty a month later to two felonies: wire fraud and theft of valor.

His sentencing is scheduled for February; he faces up to 21 years in prison.

Owens’s sister plans to be at the hearing, flanked by her brother’s Marine buddies.

She has a message for Blackstone: “I want you to apologize to each of these Marines, because you are not one of them.”

“I want him to face those people that he dishonored,” she said.