A haggard Philip Seymour Hoffman knew he was trapped in a downward spiral, readily admitting, “I’m a heroin addict,’’ to a stranger two weeks ago.
The Oscar-winning actor made the bizarre admission to magazine publisher John Arundel at the Sundance Film Festival in Park City, Utah, after the businessman didn’t immediately recognize him and asked what he did for a living.
“He said, ‘I’m a heroin addict,’ ” the Washington Life Magazine co-publisher recalled for The Post on Monday.
Arundel said Hoffman then took off his “sloppy hat” and the publisher realized his mistake and said, “Oh, you’re Philip Seymour Hoffman.”
“Bingo!” the actor replied, according to Arundel.
Before Hoffman walked away, Arundel recalled, the “Capote’’ actor added, “I just got out of rehab.”
“Obviously, he wanted people to know he was in recovery mode,’’ Arundel said.
Or at least think he was. In reality, Hoffman — who had struggled with drug and alcohol addiction since his early 20s — was in the middle of a relapse that claimed his life at age 46 on Sunday.
His addiction had gotten so bad that Hoffman’s girlfriend of 14 years, costume designer Mimi O’Donnell, had kicked him out of the Jane Street pad in Greenwich Village where they lived with their three young kids, pals said.
“It was known that he was struggling to stay sober, and his wife had given him some tough love and told him he needed some time away from the kids and to get straight again,’’ a Hollywood source told The Post.
The screen and stage star began renting a $9,800-a-month pad on Bethune Street, less than three blocks away, around three months ago, neighbors said.
Hoffman was found dead of an apparent heroin overdose in a bathroom of that apartment, with a hypodermic needle still sticking out of his left forearm.
Cops recovered more than 20 empty heroin envelopes from the apartment, a plastic cup with 20 used syringes in it, at least 50 more envelopes of heroin and bags of fresh needles, sources said. A charred spoon was found in the sink.
“He was apparently in the throes of a major heroin addiction,’’ a law-enforcement source said.
The actor — known for his vivid portrayals of troubled souls — had said he had been clean for more than 20 years before suffering a relapse in 2012 and entering rehab for 10 days last year.
A source who was on the same 5:30 a.m. flight as Hoffman out of Los Angeles International Airport last month said the dad of three was in first class knocking back bloody marys.
And three days ago, Hoffman was spotted looking “drunk and disheveled” in a bar in downtown Atlanta, sources told TMZ.
The star was making “multiple trips’’ to the bathroom, a source said. On the flight home from Atlanta, he was spotted passed out in his seat.
Hoffman was supposed to be at the Jane Street pad at 9 a.m. Sunday to pick up son Cooper, 10, and daughters Tallulah, 7, and Willa, 5, sources said.
O’Donnell told cops she last saw the actor on the street Saturday afternoon, then talked to him by phone at 10 p.m. — and he seemed high, sources said.
When he failed to show the next morning, she got worried and started calling around.
Hoffman’s playwright pal, David Bar Katz, and the actor’s personal assistant, Isabella Wing-Davey, discovered his body in the bathroom, sources said.
Hoffman, a native of upstate Fairport, was discovered in his underwear lying on his right side on the bathroom floor.
“He was cold” and had been there “for hours,” sources said.
Katz and Wing-Davey told cops they didn’t know how often Hoffman used drugs or where he got them, sources said.
Neither responded to requests for comment.
Wing-Davey was spotted Monday afternoon coming out of the Jane Street home.
Actress and family friend Cate Blanchett, who appeared with Hoffman in 1999’s “The Talented Mr. Ripley,” also showed up there laden with toys for the three children.
Blanchett exited a black Cadillac XTS carrying two huge bags from FAO Schwarz and a telescope under her arm. Her driver carried in a third bag of toys. She declined comment.
A pastor named Dan Martin showed up minutes later to counsel the family.
Hoffman’s body remained at the morgue Monday, an autopsy still incomplete, officials said.
Broadway will dim its lights in his memory Wednesday night.
Additional reporting by Kevin Sheehan, Lorena Mongelli and Kate Sheehy