"The way Osmonds survive is we keep singing," she told the audience at the Flamingo Las Vegas, performing one day after the funeral. "That's what we want to do tonight. I know my son would want that and this show is for him."
The crowd in the sold-out showroom applauded her throughout the 90-minute show, giving her a standing ovation when brother Donny said, "I think we need to give a big round of applause for my sister for even coming on stage."
Though saying the show would be a little different than others, Osmond fought through her emotions and remained largely on schedule. Taking a moment to introduce an opera song, she spoke of her Mormon faith helping her through the past week before dedicating the song to her son Michael Bryan, 18, whom she called "my angel." Michael took his own life on Feb. 26.
While going back to change into her outfit for the song she told herself to "pull it together."
With Marie off stage, Donny marveled at her ability to perform Tuesday, calling her a "strong woman" and saying, "I hope you all appreciate what she's going through tonight."
But despite their grief, the duo did have fun on stage, performing in a dance-off, with Marie joking about her brother's dancing skills. Donny was very quick to point out that he won Dancing With the Stars. Marie, in turn, challenged her brother to dance in heels as she had done on the show.
As the Vegas performance neared an end, Marie continued to smile but appeared overcome with emotion as she wiped away tears and struggled to finish the evening's final song, "It Takes Two".
After the music stopped and crowd came to its feet, Donny simply walked to his sister and hugged her.