Billy Crystal broke down at Robin Williams' memorial service.

An insider told US Weekly: "He was in tears."

While a close friend of the Williams family told People.com: "The ceremony was such a beautiful tribute and celebration of Robin's life. There was so much joy as well as tears. He touched so many, many people's lives and brought so much happiness and light."

According to the site, guests - including Bette Midler, Whoopi Goldberg, Ben Stiller, George Lucas, Penny Marshall, Danny DeVito as well as Robin's children Zak, 31, Zelda, 25, and Cody, 22 and his widow Susan Schneider - received heartfelt souvenir ribbon wristbands from the memorial that read: "Love the stillness of life."

During the ceremony, Susan opened up about her relationship with her late husband and in a "moving" speech shared details about the day she met the 'Good Will Hunting' star.

The source explained: "One of the most moving parts was when Susan recounted the day they met at the Apple store.

"They smiled at each other from across the room, which turned into a conversation and them becoming best friends from that moment on."

The 63-year-old actor was found hanged at his home in August amid reports he had been struggling to overcome his alcohol addiction.

Susan later revealed in a statement that the star had been showing "the early stages of Parkinson's Disease, which he was not yet ready to share publicly."