This article contains spoilers for the Netflix documentary “Tell Me Who I Am,” available Friday.

When Alex Lewis woke from a six-week coma following a motorcycle accident in 1982, the first person he saw was his identical 18-year-old twin, Marcus.

“Hello Marky,” said Alex. Within seconds, a tall, ungainly woman in her 50s bore down on the patient in hysterics.

“Who is that?” Alex asked his brother, scared by her frenzied manner.

“She is our mother,” replied Marcus.

Soon doctors realized that Alex’s brain injuries were so severe, he could not remember anything or anyone but Marcus. Everything else was a mystery.

Remarkably, that altered state allowed Marcus to give his brother a clean slate. For more than 12 years, he conducted an elaborate deception to protect Alex from the sordid reality of their childhood: Beginning when they were 6 years old, their mother had sexually abused the twins and allowed them to be tortured by a pedophile ring.

As chronicled in the new documentary “Tell Me Who I Am,” Marcus concocted an alternative life, conjuring happy memories that never happened.

“I slowly fell into it because Alex was emotionally disturbed after the accident,” Marcus, now 55, told The Post. “He initially had the mental age of a 6-to 9-year-old. Why would I give him information he [couldn’t] handle? It was my gift. I did it out of love for him.”

He painted a picture of a happy life, full of annual family vacations — which actually never happened.

“I would ask about holidays and Marcus gave me the impression we went away every year, and that we had a loving family,” Alex told The Post. “In my naiveté, that was all that I needed.”

Once, when Alex asked his twin if their mother, Jill Dudley, was a good parent, Marcus simply answered: “Our mother is cool.”

The party-loving aristocrat, who was distantly related to former British Prime Minister Clement Attlee, was, Alex said, “larger than life” and part of a bohemian social circle.

“She was the mother I was presented with at 18 and I built up a friendly relationship with her,” recalled Alex.

Jill, a compulsive hoarder, died of cancer in March 1995 at the age of 63, five years after the twins’ accountant-stepfather, Jack, suffered a fatal heart attack. The boys’ biological father was killed in a car crash when they were just 3 days old.

After her death, it was left to the brothers to empty out Duke’s Cottage, the mansion in Sussex, England, outside London where they had been raised.

‘Children will accept anything because they love their parents…and they think what their parents are doing is part of growing up’

The duo found 200 cartons of cigarettes, jam jars stuffed with cash, more money sewn into the hems of curtains — and a large number of sex toys in a locked wardrobe.

“Marcus did not seem shocked, ” Alex recalls in the documentary.

In the attic, they discovered dozens of presents — obviously intended for them — from godparents, aunts and uncles, which Jill had stored, largely unopened.

Then, locked in a cupboard within a cupboard, they came upon the photo that began to break open the truth of their childhood.

It was a picture of a naked Alex and Marcus, around 11 years old, with their heads cut out.

Alex confronted Marcus: “Did Mummy abuse us or not?”

Marcus nodded a yes and abruptly fled into the garden.

“I just cried and cried and cried for days. I didn’t know what to do,” Alex says in the film.

But for nearly two decades, Marcus refused to share any more details of what had happened. As he told The Post, it was out of self-preservation.

Planting all those false memories for his brother had helped Marcus as well, because he slowly started to believe them himself.

Initially, Alex was upset with Marcus. “The one person I trusted 100 percent had betrayed me,” he says in the documentary. “I was angry with him . . . At 32, I had to restructure my whole life again.”

Alex decided to launch his own investigation into Jill.

Sorting through papers at Duke’s Cottage, he came across explicit letters between Jill and a string of lovers. She had, at one point, put the twins in foster care so she could pursue erotic adventures.

“She was out shagging, drinking and partying,” Marcus told the Sunday Times of London in 2013, after he and Alex co-wrote a book, also titled “Tell Me Who I Am,” about their experience.

“Her life revolved around sex,” Alex says in the movie. “I did love my mother but it was very difficult to marry up the two mums — the one I knew [after the accident] and the one I found out about.”

‘The one person I trusted 100 percent had betrayed me…at 32, I had to restructure my whole life again’

Alex, who lives in West Sussex, began to have suicidal thoughts. Mercifully, his wife and their two sons helped him through it.

The brothers remained close, forming a multimillion-dollar hotel partnership with properties in Zanzibar and London. In 2014, after their book was published, director Ed Perkins approached them about doing a documentary.

Sure that this was his chance to coax from Marcus the missing details, Alex pushed him to do it.

“At first I felt I could do the movie like we’d done the book — and still get away without filling in all the pieces,” Marcus recalled. “But then . . . I thought: ‘F–k it.’ ”

Still, he couldn’t bring himself to tell Alex everything face-to-face. Instead, he agreed to share the story on video, for Alex to watch.

In the most disturbing scene in the documentary, Marcus delivers his four-minute monologue. He tells how, when they were young, Jill would “take us into her bed . . . make us touch each other . . . masturbate us” and do “what no mother should ever do to a child.”

He says she would “pass us around to her friends.” Typically, that meant going to dinner at someone’s house, then leaving one twin or the other with the host.

“Some strange man that I’d never met … would take me into his bed and touch me and rape me,” Marcus recalls in the film.

When Jill picked him up in the morning, “I was silent … and then it would happen again and again.”

Although they never discussed it as children, Marcus knew it was happening to Alex as well.

“I would be lying in my bed in my room. Alex wouldn’t be there,” said Marcus. “He would be staying with a ‘friend.’ And this was something that was a normality in our lives.”

As is many times the case with abused children, Marcus simply accepted their fate.

“Children will accept anything because they love their parents. And they think what their parents are doing is part of growing up,” he says in the film.

Marcus explained that the “free spirit” climate of 1960s and 1970s London helped facilitate the crimes against him and Alex.

“It was ‘anything goes,’ ” he said, adding that he and Alex were expected to serve drinks at Jill’s parties, where the guests were often well-known artists. At one bash, Marcus recalled, he wet his pants in terror after seeing a man who had abused him a few months earlier.

The abuse ended after 14-year-old Marcus was left at the home of an artist. When the pedophile started to touch the teen’s genitals, he pushed him away and said, “Stop.” Marcus escaped and traveled home by train, slipping into his bed beside Alex’s in the early hours of the morning.

Jill seemed surprised to see him at breakfast but said nothing.

“That’s how it stopped,” Marcus explains in the film.

The documentary shows Alex watching his brother’s chilling reveal on a laptop. When the twins are reunited afterward, they tearfully embrace.

“No more lies,” Alex tells Marcus. “No more secrets.”

Now that the truth is out, Marcus can express his fury.

“F–k you, Mother!” he rages in the film, furious Jill went to her grave unpunished. “She’s got away with it.”

Marcus believes that their stepfather was unaware of the abuse. “He was a very contentious, difficult man, but I don’t think he knew,” Marcus — who now lives with his wife and young son and daughter in London — told The Post.

As for Alex, he is baffled by the mother he “only knew for a short space of time” and constantly wonders how one could “get into that space” of abusing children.

Meanwhile, he says that he now understands — and appreciates — his brother’s compassionate motivation to give him a fresh start.

“When I finally found out what he’d been carrying all these years and what he’d been prepared to do for me, it was truly inspiring,” Alex added. “I realized the enormity of what he had sacrificed.”