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During an interview with Diane Sawyer that aired on October 28, Perry discussed his book Friends, Lovers, and the Big Terrible Thing, his addiction and his time on Friends.
The actor recalled the beginning of the series when the creators took everyone out to lunch separately and asked them about themselves.
Perry told them that he had "a lot of trouble with women" and that led to who Chandler Bing became as a character.
Sawyer showed scenes from Friends including a clip from "The One with the Blackout" when Chandler gets stuck in an ATM vestibule with Jill Goodacre.
"I don't really watch the show so that was really fun to look at," Perry said after laughing at the scene.
As the show went on, Perry's addiction worsened and the effects of his struggles could be seen on screen.
With Perry's consent, they watched a scene from "The One at the Beach" and he put his hand to his forehead, getting emotional.
"It's very hard to watch that because in this weird way I feel sorry for that guy," he said. "That's a guy that's out of control."
"He's going through too much and it's me and I remember that and I didn't understand what was going on," Perry continued.
"I'm so grateful to not be that anymore but it's hard to watch that."
Sawyer noted that he had no trouble with his lines, his comedic timing or showing up to set.
"Early on, yes," Perry confirmed. "I made a rule that I would never drink or take anything at work. So, I would never do that but I would show up blindly hungover, shaking."
Later on, when the Canadian actor was in rehab, he would be driven from the treatment centre to the set every day, including when they were filming Monica and Chandler's wedding.
Perry was then shown a scene of the ceremony from "The One with Monica and Chandler's Wedding: Part 2" and it brought a smile to his face.
"That was pretty good. I'll watch that scene over and over, that was good. I looked good, sober," he said. "That was fun to watch."
He also noted that the scene was a moment when Chandler was "overtaking" Perry in his own life by getting married and then having kids.
"The end of Friends meant the end of an era and work like that was going to be hard to find but I was sober and I stayed sober for a pretty long time," Perry said.
When the Friends reunion was released, Sawyer noted that people were worried about Perry.
"A couple days before that I had emergency dental surgery which did all sorts of things," the actor explained. "The dental surgery just made my mouth feel like fire and it sounded like my voice was off. I couldn't not show up so what I chose to do was just go and do the best that I could."
Perry shared that because he was on Friends, people are more willing to listen to him when he speaks about his struggles with addiction.
"I've got to take advantage of that. I've got to help as many people as I can."
What is Matthew Perry's book?
Friends, Lovers, and the Big Terrible Thing is Perry's memoir and it includes a forward by Friends co-star Lisa Kudrow.
In the memoir, he shares the intimate details of his darkest days, his struggles with addiction, his friends, his lovers and his time on the popular sitcom.
He even took a shot at fellow Canadian Keanu Reeves: "Why is it that the original thinkers like River Phoenix and Heath Ledger die, but Keanu Reeves still walks among us?"
After that expert was released, Perry walked back his comment and apologized.
"I'm actually a big fan of Keanu," he said in a statement. "I just chose a random name, my mistake. I apologize. I should have used my own name instead."
Perry's book, Friends, Lovers, and the Big Terrible Thing, comes out on November 1.
If you or someone you know is struggling with alcohol or substance use, help is available across the provinces and territories. If you need immediate assistance, please call 911 or go to your nearest hospital.
If you or someone you know is struggling with alcohol or substance use, help and additional resources are available. If you need immediate assistance, please call 911 or go to your nearest hospital.