René Angélil and Céline Dion
Willi Schneider/REX USA
08/21/2014 AT 04:40 PM EDT
Those close to Céline Dion
were not shocked to learn the singer decided to postpone
all of her show business activities indefinitely to care for her husband, René Angélil.
"They are each other's lives," friend Robin Leach tells PEOPLE of Dion, 46, and Angélil, 72, who currently reside in Las Vegas with their three children, René Charles, 13, and fraternal twins Eddy and Nelson, 3. "He and her family come first and she's always made that clear."
Leach adds that Dion had been contemplating an extended leave ever since Angélil underwent surgery
in December to remove a cancerous tumor from his throat.
"René was making great progress and was out and about," Leach says. But the recovery process remains ongoing.
"Last time I saw him, he was very thin and frail," she adds. "Céline had to take a step back, and her decision is a realization that you have to hold onto everything while you've got it."
But when it comes to Angélil's prognosis, the family is "trying to stay positive," an insider says. "They're optimistic. "
With reporting by MARK GRAY