The late 'Glee' star Corey Monteith started using alcohol and drugs from the age of 13, according to claims in the bombshell docuseries 'The Price of Glee'

The pal said: "When he got the part, he was supposed to be this good kid playing this role. He didn't want his past getting out.

"The beginning of his success with Glee, we were really being told, 'Don't let it out that he's got the drugs and alcohol problem.'"

However, his roommate Justin Neill, alleged the actor was more "flippant" about his drug and alcohol use with him.

He recalled: "When Cory moved in, it was New Year's Eve 2008. The next day, he said it in such a flippant manner, something about drug use and he wanted us to know right away that he had a past, he's sober now and that this is a big part of his life."

Corey's drug use began in the years proceeding his parents' divorce.

When he was 19, his mother and friends staged an intervention, with him starting rehab in 2001.

Corey made his substance issues public at the end of the second series of 'Glee', stating: "I feel like I had to step in at some point and relate to people with my experience and where I come from."

Neill also claimed Corey struggled with the intensity of fame and grew "more and more isolated".

He alleged: "There was a period where it seemed Cory was getting more and more isolated.

"He just got to the point where he just hated fame. [He said], 'I'm just so tired, I want to rest for a bit. I'm sick of singing of these songs,'

and I remember him specifically saying, 'I wouldn't wish fame on my worst enemy.'"

The ex-roommate alleged the Canadian star started to struggle to separate the real Corey from his alter ego and fell into a really dark place.

Neill added: "I'd seen the fame, but I didn't realise how hard it was for him until then. I think with that level of fame, you lose sight of who you are. To every single person, he wasn't Cory anymore. He was now Finn. We just knew he wasn't in the best place."