Singer Celine Dion has cancelled all her work engagements indefinitely to stay by her ailing 72-year-old spouse Rene Angelil's side, and to support their sons as family always comes first for her.

The 46-year-old singer's husband underwent treatment for a second bout of throat cancer in December, and she has been considering a break since his surgery. But she has now finally slowed down to devote time to him, and their sons - Rene Charles, 13, and three-year-old twins Eddy and Nelson.

"They are each other's lives. He and her family come first and she's always made that clear," Dion's friend Robin Leach told people.com.

"Rene was making great progress and was out and about. Last time I saw him, he was very thin and frail. Celine had to take a step back, and her decision is a realisation that you have to hold onto everything while you've got it," added Leach.

Despite Angelil's condition, his family is "optimistic".