Fawaz told the Daily Telegraph of London that he and Michael had planned to spend Christmas Day together.
"We were supposed to be going for Christmas lunch. I went round there to wake him up and he was just gone, lying peacefully in bed. We don't know what happened yet," he told the Telegraph.
The singer's longtime manager, Michael Lippman, also confirmed to the Hollywood Reporter that heart failure caused the singer's death.
Lippman said he received a call on Christmas morning notifying him that Michael had been found "in bed, lying peacefully".
"I'm devastated," he said.
"[There was] no foul play whatsoever."
Thames Valley Police said they were called to a property in Goring-on-Thames shortly before 2pm local time, adding: "Sadly, a 53-year-old man was confirmed deceased at the scene."
"It is with great sadness that we can confirm our beloved son, brother and friend George passed away peacefully at home over the Christmas period," his representative said in a statement to the BBC. "The family would ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage."
UK police initially said his death was "unexplained but not suspicious".
The reclusive superstar was reportedly struggling with his weight in the week's leading up to his death.
The star was rarely spotted in public in recent months, according to TMZ.
Health wasn't the only issue plaguing the star.
In 2006, he was arrested for drug possession, but was released. He was arrested over drugs again in 2008 and was caught driving under the influence of drugs in the UK in 2010.
Just weeks before he died, a photo emerged of Michael dining at an Oxfordshire restaurant with friends on September 14, 2016.
He appeared tired and bloated, at a time when whispers had been circulating about his health.
Michael was dogged by health scares during the past decade of his life.
As recently as last year, he was forced to publicly deny new allegations about drug-taking, describing them as "highly inaccurate".
Michael nearly died from pneumonia in late 2011. After treatment in a Vienna hospital, he made a tearful appearance outside his London home and said it had been "touch and go"
whether he lived.
Doctors had performed a tracheotomy to keep his airways open and he was unconscious for some of his spell in hospital.
The star pulled out of a series of concerts because of his health issues and he later revealed the massive struggle he faced to recover, including learning to walk again.
"I didn't get myself checked out. I took it for granted that I'd just fought off flu," he said in a 2012 interview.
"I went and played for another three weeks in Europe.
"And then one afternoon I was having lunch and suddenly felt really odd and said to everyone that I need to go and lay down for half an hour on my own.
"And that's the last thing I remember for five weeks. It was three weeks of them trying to save my life and two weeks awake.
"I literally had to learn to walk again and weird stuff, because when they keep you sedated for that long your muscles atrophy at an incredible rate. And I just woke up like this feeble old man."
But that wasn't the end of his battle.
He returned to hospital just 18 months later with a head injury after he bizarrely fell from his vehicle on the M1 motorway outside London.
