Cory Monteith, who died from a lethal mix of heroin and alcohol at age 31, had spoken openly about his past addictions but secretly he was battling other demons.

Days after his death, friends are revealing he struggled with fame and the lifestyle that comes with being rich and famous in Hollywood.

"Fame was hard for him," a friend to People. "It was something he knew he deserved but somehow he never quite knew how to handle."

"They worked hard and partied hard," says a Glee source, adding that in real life, "these aren't high school kids. They are adults who enjoyed the perks of fame."

Monteith was found deceased in his room at the Fairmont Pacific Rim hotel in downtown Vancouver, British Columbia, shortly after noon on July 13. He had checked into the hotel on July 6 and had been expected to check out on the 13th. When he had not done so, hotel staff checked his room and found him deceased.

"We are so saddened to confirm that the reports on the death of Cory Monteith are accurate," his rep said in a statement. "We are in shock and mourning this tragic loss."

Following Monteith's shocking and sudden death, his girlfriend and Glee costar Lea Michele is grieving.

"We ask that everyone kindly respect Lea's privacy during this devastating time," a rep for the actress told PEOPLE.

Cory Monteith Dead: Celebs React on Twitter

Monteith entered rehab earlier this year for substance abuse, after previously seeking help for addiction at age 19.

Following his decision in late March, Michele, 26, stood by her man.

"I love and support Cory and will stand by him through this," she said in a statement at the time.

 In May, Monteith and Michele were photographed vacationing in Puerto Vallarta, Mexico, together.

Monteith had seemed to have turned a corner recently, emerging from rehab and appearing last month with Michele at a charity ball.