In her first interview since her husband’s suicide last August, Susan Williams, widow of the actor, Robin Williams, has opened up about her late husband's health struggles and the months leading up to his death.

Speaking to ABC’s Good Morning America, Williams said that “it was not depression that killed Robin,” but other, ongoing health problems.

Robin Williams was a hugely popular actor and comedian, thriving in roles from family films such as Mrs. Doubtfire, as well as those with a heavier tone, such as Good Will Hunting - for which he was awarded an Oscar.

He was known to have previously suffered from alcoholism, drug addiction and mental health problems.

Williams explained that, contrary to what was broadcast at the time of her husband’s death, it was neither depression, nor alcohol or drug addiction that caused the 63-year-old to commit suicide – he’d been sober for eight years, she says.

Autopsy results in fact revealed that the actor had been suffering from a disease called Lewy body dementia and had also been diagnosed with Parkinson’s disease.

Williams says the actor was “disintegrating before my eyes” and that the couple were “living a nightmare” in the months leading up to his death.

“It was not depression that killed Robin,” Williams says in another interview with People magazine, “depression was one of let’s call it 50 symptoms and it was a small one”.

His physical symptoms included stiffness, slumping, a shuffling gait and “losing his ability in his voice”, describes Williams.

Speaking in the ABC interview to Amy Robach about the Oscar-winning actor’s death, Williams says: “he was the bravest man I know,” but “my best friend was sinking” and in the final month “it was like the dam broke.”

Williams said that, from November 2013, it felt as though her husband had a new ailment every month, and admits to thinking he was being a hypochondriac.

“It was like playing Whac–a-Mole. Which symptom is it this month? I thought, ‘Is my husband a hypochondriac?’ We’re chasing it and there’s no answers.” she recalls.

When he was finally diagnosed with early onset Parkinson’s in May 2014, the couple felt a “sense of relief” just to have an answer for the “endless parade of symptoms”.

But when asked if the actor had hinted a desire to end his life, Williams says: “No. Not even -- no. No.”

She recalls her final conversation with her husband, the night before his death, saying that she was in bed and he had offered her a foot massage.

"I said, ‘It's OK, honey....You don't have to tonight."

"And I'll never forget the look in his eyes of just, sad because he wanted to," she says. 

“Then he came back in the room a couple of times....and he said -- and then he laughed. And he said, ‘Goodnight, my love.’ And I said, ‘Goodnight, my love.’"

When Robach asked Williams if she thought her husband’s suicide was a way of taking back the reins of his life, she replied: “In my option, oh yeah.”

"I mean, there are many reasons. Believe me. I've thought about this. Of what was going on in his mind, what made him ultimately commit... you know, to do that act,” she continues.

"If Robin was lucky, he would've had maybe three years left," the actor's widow says. "And they would've been hard years. And it's a good chance he would've been locked up."

“I don’t blame him one bit. I don’t blame him one bit,” she says.

After the emergency services left and Williams was able to see her husband for the final time, she recalls saying to him:

“I forgive you 50 billion percent, with all my heart. You're the bravest man I've ever known.”

Watch the interview, below.