WITH his life in a down­ward spiral, troubled MACAULAY CULKIN tried to end it all by at­tempting suicide, sources tell The ENQUIRER.

Hopelessly hooked on heroin and the powerful prescription painkiller oxycodone, the 32-year-old former child star nearly overdosed on drugs, as The ENQUIRER reported in August.

But now an eyewitness re­veals graphic new details of the overdose, claiming the onetime “Home Alone” tyke “was talking about killing himself – saying he had ‘nothing to live for.’ ”

“Macaulay was shooting heroin and talking about taking his own life,” the source, who was with Culkin at his apartment in New York’s SoHo neighborhood during the chilling incident, told The ENQUIRER.

“He was also taking pills, and if he hadn’t stopped, his heart would have given out.

“He was in a drugged-up state, but Macaulay clearly knew what he was doing. I’m convinced he was trying to kill himself!”

The eyewitness says Culkin was sob­bing uncontrollably over the end of his eight-year relation­ship with “Black Swan” beauty Mila Kunis, who is now dating her “That ’70s Show” co-star Ash­ton Kutcher.

“Fortunately, Ma­caulay wasn’t alone, otherwise he likely would have ended up dead,” said the source. “There was blood on him from shooting up. It was a horrible situation, and a near-OD.”

Perhaps even more frightening, Macaulay is still in denial.

“After the incident it was clear that Macaulay needed psychological help, but he refuses to admit he has a problem,” said the source.

“The fact is that his life is at a dead end, his career is in the toilet and he can’t get over Mila, who left him because of his drug use at the time.

“The guy is going to wind up like John Belushi or River Phoenix if he doesn’t get himself into rehab.”

Culkin announced his re­tirement from movies at age 14 and has done little work since then, living off the money from “Home Alone” and its 1992 sequel.

In 2006, he published “Junior,” a semi-autobio­graphical novel in which he chillingly writes about contemplating suicide by overdosing on pills.

Experts who have not treated Culkin told The ENQUIRER that his down­ward spiral will likely end in death.

Culkin is “dealing with a lethal com­bination of drugs, and to say that he’s dying is not an understatement,” Dr. Norman S. Miller, an addiction psychi­atrist and professor at the University of Florida told The ENQUIRER.

“He has a choice. He can recover if he gets help, but right now there is no question he’s dying from his addic­tion.”

Dr. Gregory Smith, an L.A.-based addiction expert and producer of the award-winning film “American Ad­dict,” added: “He’s using a deadly combination of drugs. We’re going to see yet another Hollywood celebrity dying of an overdose from a heart at­tack or respiratory distress.”