In their only interview about the death of their father GEORGE, DONNY and MARIE OSMOND open up this morning to our JANN CARL just moments before boarding a plane to Utah where the 90-year-old Osmond patriarch died early Tuesday morning.

"He was a man of integrity, of honor," a tearful Marie tells Jann. "He was the best man I've ever known."

"His life wasn't perfect," Donny tells Jann. "But look at what he's done with it."

Marie, who was the only Osmond daughter, says she always hoped to make her dad happy. "I wanted my dad to be proud of me," she says.

"Oh he is!" Donny assures her.

Their mom OLIVE died in 2004 at the age of 79 and Donny says he believes his parents are now reunited. "We know our mom and dad are together again," he says.

For more on Donny and Marie's emotional interview, watch tonight's ET.