"She was yelling, 'Is it true, is it true about Cory?'" Ann McGregor tells PEOPLE

Five years after former Glee star Cory Monteith died of a heroin overdose in 2013, his mother Ann McGregor can still recall, with chilling detail, the moment she heard the news.

“I got a call from Lea [Michele, Monteith’s girlfriend of over a year] and she was screaming on the phone,” says McGregor, 67, in this week’s issue of PEOPLE, on stands Friday. “She was yelling, ‘Is it true, is it true about Cory?’ and I said, ‘What about Cory?’ I had heard nothing. And then police knocked on my front door.”

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Lea Michele and Cory Monteith
| Credit: Dimitrios Kambouris/WireImage

When she heard the news, “I went into a state of numbness,” McGregor recalls. “I just shut off all emotions, and I was numb.”

As days and weeks passed, “I knew it was real, but there were times when I could lie to myself and say, ‘He’s in L.A., he’ll call me soon.’ I’m still always hanging on edge. When you lose someone who is such a big part of you, you lose all purpose for living.”

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Cory Monteith and Lea Michele
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Monteith, who had a history of drug use and had been in rehab three times, was just 31 when his body was found in Vancouver hotel room with traces of morphine, codeine and heroin present.

But just before his death, Monteith had been making plans for the future, renting an apartment in Vancouver to move into once his contract with Glee was up, and even talking to his mom about family.

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Cory Monteith and Ann McGregor
| Credit: Courtesy Ann Mcgregor

“Cory wanted a wife and kids,” says McGregor. “He would have made a beautiful father. He had accomplished so much. He was ready to step out of Hollywood and really live. He had so much to look forward to.”

  • For more on Cory Monteith, pick up this week’s issue of PEOPLE, on stands Friday

Now, McGregor is focused on the keeping Monteith’s passions outside of acting alive, including his work with Project Limelight, a non-profit, free performing arts program for youths, and St. James Music Academy, which provides classical music education for at-risk children. McGregor also works with Amber Academy, a non-profit in her community that empowers youth through fine arts.

“Cory didn’t want to die,” McGregor says. “There is no doubt about that. But he’s carried in people’s hearts forever.”