Celine Dion has been trying her best to stay strong for her children ever since her husband Rene Angelil passed away last Thursday to cancer, but as the funeral approaches, it's obviously a very difficult time for the family.

"She's extremely heartbroken," a source close to the iconic singer told People. "But she's very good at and has always been about putting on a brave face."

Dion and Angelil were married for 21 years and had three sons together, Rene-Charles, 14, and 5-year-old twins Eddy and Nelson. Angelil's funeral is set to take place Friday, Jan. 22, and it's been hard for the boys.

"They're obviously grieving," said another source close to the family, according to Perez Hilton. "Rene-Charles, being a teenager, has had a more difficult time with the situation than the twins, who are so young."

"I know Celine truly believes that he will eternally be with her and with the kids through everything," added her longtime stylist and close friend Annie Horth.

Last March, when he was still suffering, Dion explained how she was trying to stay strong for not only him, but the three children as well.

"My kids need me a lot, my husband needs me and I need to keep going," she told People at the time. "If I'm too withdrawn, I don't think my family will overcome that.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."

Angelil, who was also Dion's manager for more than 30 years, has requested that his funeral be held at Notre-Dame Basilica in Motreal, which is the same place he wed Dion in 1994, as HNGN previously reported. According to his obituary, he chose this location because it is "where 21 years ago he chose to marry the one who will remain as the great love of his life, the artist for which he had the most respect, the woman who gave him light and happiness until his very last breath."

Despite rumors, Dion will not be performing at his funeral. She will return to Las Vegas to continue her residency at Caesars Palace Feb. 23, just a few weeks after his funeral.

"That's what Rene would want. He wants her to perform and come back," another source told People. "He knew her better than anybody and he probably knows that's what she needs too, to perform."