Robin Williams played many iconic roles, but his most important role was a family man. Now, for the first time since his tragic passing in 2014, his wife Susan Williams has opened up about his death in an emotional interview. Speaking on Good Morning America this week, Susan revealed  that she had forgiven him for taking his own life. She also revealed that it was not depression that took the Oscar winner's life as was widely reported, but dementia. She said: "Lewy body dementia killed Robin. It's what took his life. "And that's what I've spent the last year trying to get to the bottom of: what took my husband's life." She revealed that in the last few week's of the 63-year-old's life, doctors were planning to check Robin into a neuro-cognitive facility for the treatment of this disease. When asked if Robin was "losing his mind", she replied: "He was aware of it. He was keeping it together as best he could, but the last month he could not. It was like the dam broke. " Susan opened up about how quickly the disease took over. She said: "In November 2013, he had a little gut pain. Next month it was another symptom. It was like this endless parade of symptoms. "And not all of them would raise their head at once. It was like playing whack-a-mole. 'Which symptom is it this month?', I thought. Is my husband a hypochondriac? "We're chasing it and there's no answers .... We tried everything." According to the Alzheimer's Assn, Lewy body dementia is the third most common form of dementia behind Alzheimer's and vascular dementia. Although Robin's assistant was the one who found the body on August 11, 2014, Susan saw him before the authorities arrived. She said: "I got to tell him, I forgive you, with all my heart. You're the greatest man I've ever known. "You know, we were living a nightmare." https://www.youtube.com/watch?v=sVq0V7rKImk Video via YouTube/ABCNews