On Friday, the Sundance Film Festival in Park City, UT debuted Robin Williams: Come Inside My Mind, a tragic but fascinating documentary about the soft-spoken actor’s life and untimely death. The film, which includes rare footage and interviews, revealed new information about the Mrs. Doubtfire star, including how he sobered up following his friend John Belushi‘s death.

In 1982 — after a day on the set of Mork & Mindy — Robin ended up drinking and doing cocaine with the Saturday Night Live alum at a Chateau Marmont bungalow. Within hours of meeting up, John died from a drug overdose.

The next morning, Robin’s costar Pam Dawber — who played Mindy — broke the news to him on set. Shaken by his death, Robin made a promise to himself to quit drinking and drugs cold turkey. “It sobered the s–t out of me,” he said.

Robin took his own life on Aug. 11, 2014, at the age of 63, and his struggles with depression and mental health came out frequently in the roles he played. He talked about how working as a comedian is a double-edged sword. While making other people laugh, Robin said there was another side to working as a comedian.

“Oh, [comedians] have a dark side, I mean, because they’re looking at that,” he said on NPR. “In the process of looking for comedy, you have to be deeply honest. And in doing that, you’ll find out here’s the other side. You’ll be looking under the rock occasionally for the laughter. So they have a depressed side. But is it always the sad clown thing? No. But I find comics to be pretty honest people in terms of looking at stuff from both sides or all sides.”

Following his death, his wife Susan Schneider released a statement. “This morning, I lost my husband and my best friend,” she wrote. “While the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken.”

Suicide hot line: If you or someone you know is contemplating suicide, call the National Suicide Prevention Lifeline at 1-800-273-8255.