The 46-year-old Canadian singing superstar made the announcement during an emotional interview with ABC's Good Morning America, in which she described the severity of Angélil's condition.
The 73-year-old, who used to manage Dion's career, was diagnosed with throat cancer for a second time in 2013.
Describes 'major' surgery
"Rene could not talk and he could not swallow. The surgery was major," Dion said in the segment that aired Wednesday morning.
"I had to leave him behind because he wanted me to start the shows again," said Dion, who tearfully described how she was torn between Angélil's bedside and her popular residency at Caesar's Palace in Las Vegas – a gig she put on hold last August so she could care for her family full time.
"He can't eat. He's got a feeding tube. I have to feed him three times a day. I do this myself," said Dion, who has three children with Angélil – René-Charles, 14, and 4-year-old fraternal twins Eddy and Nelson.
Scared and worried
"I really believe that children know it all. We're afraid of explaining because we're scared, because we're worried," said Dion, who described downplaying the feeding tube to her children by asking them to participate in Angélil's care.
"I said to my children: 'You want to come and help me feed Papa today? ... Wanna help me out and hold the water? Good job Nelson. Good job Eddy.'"
Angélil makes a brief appearance in the ABC interview, walking on The Colosseum stage with Dion where she will relaunch her residency with a new show on Aug. 27.
Forty performances are scheduled through Jan. 17, 2016, according to Dion's official website.
Tickets go on sale March 28.
"I'm doing it for him. I'm doing it for my fans. I'm doing it for me," Dion said.