https://www.youtube.com/watch?v=S-XYphrgRzU
He was also life long friends with Christopher Reeve. They were accepted to Julliard together (out something like 150 applications for 2 spots, they were two students chosen).
When Reeve was lying in his hospital room paralyzed, Williams reportedly came into his room wearing a clown nose and refused to let Reeve pity himself.
Williams was up front about his alcoholism, and made many attempts to remain sober.
May God have mercy upon him.