Widow of Robin Williams Discusses His Crippling Brain Disorder

Susan Williams talks about her best friend, and the crippling diagnosis that affected his brain. Tune into World News Tonight with David Muir weeknights at 6:30 | 5:30c on ABC for breaking news, world reports, Made In America segments and other extraordinary stories. Watch more stories from World News Tonight with David Muir here: http://abcnews.go.com/WN Follow anchor David Muir across digital platforms— Facebook: https://www.facebook.com/davidmuirabc... Twitter:   / davidmuir   Instagram:   / davidmuirabc   Follow World News Tonight— Facebook:   / worldnewstonight   Twitter:   / wntonight   Instagram:   / abcworldnewstonight  "