But as the service drew near an end Monday afternoon, she stood and addressed hundreds of mourners at the Church of Jesus Christ of Latter-day Saints Chapel in Provo, Utah, who included her show business brothers, seven surviving children, and one unexpected invited guest: the biological mother of Michael, who was adopted.
"I'd just like to say thank you to everybody," she said. "As you see I have amazing support from great men, my family, my brothers. God was very wise when he put me into a family with honorable men because they have served as examples for my children."
And so, Osmond, 50, said she wanted to use this occasion of horrible grief to "honor my children."
"I'm so proud of each and every one of you," she said. "I'm proud of my son and I honor his birthmother who's here today, who gave me the greatest gift. Thank you for those beautiful 18 years."
Marie then joined all of her brothers in singing the closing hymn, "God Be with You Till We Meet Again."
George Frey / AP
Donny's InvocationHer emotional remarks came after her brother Donny and Michael's siblings spoke through tears of their memories of the teen who took his own life.
Donny, 52, choked up during the Invocation and had to take a long pause to gather himself before he said of Marie: "Bless my sister. Bless my sister and her family. May she feel my love and my comfort."
Michael's 12-year-old sister Brianna cried as she called Michael "my best friend" and "the coolest person ever."
"Michael never forgot my birthday," she said. "That's a big deal in a family that's as big as mine! ... The house was more fun when he was home. We had dance competitions to Miley Cyrus songs. He would make up words and sing along. We'd have whipped cream fights in the kitchen."
Also overcome with emotion was Michael's sister Rachael, 17, who spoke of her struggle to understand his death.
"All I had in my mind were questions, most beginning with what if, what if I had done this, what if I had done that, I shouldn't have done this, I should have done that," she said. " We always thought he was going to get married first and have kids. We wanted to go to school together next year."
A Child's MemoriesAnd out of the sadness came a moment of levity when Michael's 7-year-old sister Abigail said playfully, "My brother Michael loved ME the most."
"My brother was funny and he made me laugh," she said. "I liked playing the game Colors with Mike in our pool. My brother wrote a song about me that said I made him very happy. See, he did love me the most!"
And his brother Matthew, 10, added: "My brother had the best jokes. We used to mess around and play-fight but it was not fair because he was bigger than me so he always won."
After the funeral, a private internment was held at a local cemetery.