How Céline Dion's Children Are Coping with Dad's Loss: She's 'Putting on a Brave Face' for Them, Says Source

"She's very good at and has always been about putting on a brave face," a Dion source tells PEOPLE

Photo: Courtesy Celine Dion

Céline Dion is coping with the loss of her beloved husband René Angélil, followed by the death of her brother just two days later. Click here for the full story, only in PEOPLE.

As René Angélil's health declined over the last year, Céline Dion tried her best to stay strong for both her husband and their three sons.

"My kids need me a lot, my husband needs me and I need to keep going," she told PEOPLE last March. "If I'm too withdrawn, I don't think my family will overcome that. I have to show myself, my husband and my kids and I am strong and we're okay."

After losing Angélil last Thursday to cancer, "she's extremely heartbroken," says a source close to the "Power of Love" singer. "But she's very good at and has always been about putting on a brave face."

On Friday, son-in-law Marc Dupré, a Canadian musician married to Angélil's daughter Anne-Marie, thanked his followers on Twitter for their support. "Thank you for your sympathy messages! René was for me a model, a friend, my second father ! We will miss him. Rest in peace xx René.

For much more on Dion and Angélil's love story and how the singer is focusing on the couple's children, pick up the latest issue of PEOPLE, on newsstands Friday.

With the music manager's funeral planned for Friday, "they're obviously grieving," adds the source of Dion, René-Charles, 15, and 5-year-old twins Eddy and Nelson. "René-Charles being a teenager has had a more difficult time with the situation than the twins, who are so young."

But helping the family stay strong is the knowledge that Angélil will always be with them in spirit.

"I know Celine truly believes that he will eternally be with her and with the kids through everything," Dion's longtime stylist and friend Annie Horth tells PEOPLE.

*With reporting by JANINE RUBENSTEIN