It’s been nearly a decade sinceGlee’sCory Monteithdied fromaheroin overdoseat 31 years old, but for his good friend and former roommate Justin Neill, the loss is still difficult to bear.

“Even now, I still can’t comprehend that he’s gone,” Neill, who appears in the new docuseriesThe Price of Glee, premiering Jan. 16 on ID and discovery+, tells PEOPLE exclusively. “Cory was a great friend. And he changed my life.”

When Neill first met Monteith, he was a budding performer on the brink of stardom. AfterGleepremiered in 2009, the actor’s life changed forever.

“Cory was extremely grateful for the show and there was a level of gratitude all the time,” recalls Neill. “He had this mentality like, ‘I should be working on roofs in [his native] Canada in the snow, this wasn’t supposed to happen!’ But being human, he did have days where he was exhausted. And he needed separation and alone time. He just couldn’t be on 24/7.”

Cory Monteith and Justin Neill.Courtesy

Cory monteith roommate rollout

Continues Neill: “He wasn’t his character [football star Finn Hudson]. He was a real person. He was neurotic and generous and a goofball. And he was one of the smartest people I knew.”

Despite the success and perks, including World Series games and trips to Australia — “Cory always brought us along,” says Neill — Monteith’spast demons returnedand the actor entered rehab in April 2013.

“When we met, he waseight or nine years sober,” says Neill. “I never saw him messed up. And then when he got back from rehab, I thought great, our Cory is back. He’s doing the work, and for that, I was grateful.”

Cory Monteith and his roommate Justin Neill.Courtesy

Cory monteith roommate rollout

Monteith’s death that July"was so much bigger than I could comprehend," recalls Neill. “This just shows that sometimes even having it all isn’t enough to make someone happy.”

These days, Neill still does his best to keep the spirit of his beloved friend alive. “Cory used to give the best life advice,” he says. “I still talk to him all the time.”

For more on Cory Monteith and Justin Neill’s friendship, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribehere.

Glee cast.FOX via Getty Images

FOX’s “Glee” - Season Four

Investigation Discoveryreleased the first trailer forThe Price of Gleein December. The three-part docuseries will cover the Fox hit show and its darkbehind-the-scenes drama, including the sudden deaths of Monteith, and his costarsNaya RiveraandMark Salling.

Rivera portrayed cheerleader Santana Lopez anddied at age 33on July 13, 2020 after sheaccidentally drowned during a boating tripwith her son at a Southern California lake. Salling played jock Noah “Puck” Puckerman anddied at age 35in an apparent suicide weeks before he was scheduled to be sentenced to prison for possessing child pornography.

Despite rumors of theGleecast’s involvement, a press release for the docuseries states that no cast members would be featured on the show. Instead, the network said the episodes would feature “those outside of the cast bubble who can provide no-strings-attached perspectives, such as: relatives and friends ofGleecast members; those who were on the set and close to it such as set decorators, hairdressers, stylists and publicists; and entertainment reporters who covered the phenomenon.”

“I don’t want to say the C word — the ‘curse’ word — but that’s where your mind goes,” says one person in the trailer, as another interviewee adds, “My first reaction is blame. I still feel that there is someone to blame.”

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The Price of Gleepremieres all three episodes on Monday, January 16 at 9 p.m. ET on ID, and will be available to stream the same day on discovery+.

source: people.com