Celine Dion tried to cover up the effects of her rare illness during live performances, but said that “the lie is too heavy now.”

The Canadian chanteuse, 56, started feeling the effects of the extremely rare (SPS) about 19 years ago, but continued to perform her record-breaking Las Vegas residencies.

SPS affects only one or two people in every million people. It is a progressive autoimmune neurological disorder that causes muscle stiffness and pain spasms, and usually begins in a person’s torso before developing in the arms and legs.

Dion started noticing changes to her voice, especially during live shows. Rather than let on that something was wrong, she found ways to cover up her condition, and this is revealed in her . It airs on and follows Dion as she fights to get back on stage.

“I don’t want to sound dramatic, but I could have died,” Dion said in the feature-length documentary.

Dion added that she was taking between 60 and 90 milligrams of Valium just to function, and that was “just one” of her many medications.

“My instrument was not working, so we started to elevate the medicine,” Dion said. “I needed medicine to function. One more pill, two more pills, five more pills; too many pills. The show must go on.

“When I had to cancel shows, we had to tell the crowd, the people: ‘Why?’ It was lying, from a sinus infection to an ear infection to whatever. Sometimes, I would point my microphone toward the audience and I would make them sing it.

“There’s moments where I cheated. I tapped on the microphone, like it was the microphone’s fault,” Dion added.

The singer said: “I did what my mum said, I didn’t flinch. And there are also moments where we had to stop the show. ‘Quick change [of clothes]’ and I never came back. The lie is too heavy now.”

“Her body and her brain is overstimulated,” Dion’s sports medicine therapist Terrill Lobo says during a scene in the documentary where the singer goes into crisis and stiffens up.

The confronting scene shows Dion curled up on her side, unable to move and crying as her team administers medication.

“Every time something like this happens, it makes you feel so embarrassed,” Dion said after it passed.

The Quebec-born singer has sold more than 250 million albums worldwide, and has had hits such as, “The Power of Love,” “It’s All Coming Back to Me Now,” “My Heart Will Go On,” and “Because You Loved Me.”

I Am: Celine Dion will be available on Prime Video on June 25.