Lea Michele broke the news of Cory Monteith's tragic death to his mother.

The 'Glee' star - who had a history of drug abuse and had completed three separate stints in rehab - died of a heroin overdose five years ago and his mother Ann McGregor will never be able to forget the moment she found out the news as the 31-year-old actress, who was his girlfriend at the time, rang her up ''screaming.''

Speaking to PEOPLE.com, Ann recalled: ''I got a call from Lea and she was screaming on the phone. 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. I went into a state of numbness. I just shut off all emotions, and I was numb.''

Ann eventually came to terms with the loss of her son - who died at the age of just 31 - but she admitted there were moments afterwards where she'd convince herself that he was just living his busy life in Los Angeles and would call her ''soon.''

She explained: ''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.''

Cory and Lea - who starred alongside one another in the teenage musical series - had been dating for just over a year when he was found dead in a hotel room in Vancouver, Canada, with traces of morphine, codeine and heroin in his system.

Ann said: ''Cory wanted a wife and kids.

''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.''

Although she still thinks about Cory and recently posted a sweet tribute on the anniversary of his death, Lea is now engaged to Zandy Reich.