Robin Williams' widow Susan Schneider has spoken out about the Hollywood actor's heartbreaking final moments before his death.

Susan opened up about how she lost "the greatest love she'd ever known" when the comedy actor died in 2014.

She spoke to Hoda Kotb on the Today show about a new documentary called Robin's Wish, which talks about the actor's battle with Lewy body dementia.

The brain disease affected Robin's memory and movement control, before he tragically took his own life in August 2014, aged 63.

Susan spoke about the final months of Williams' life, and how he had to sleep separately from her before his death.

Robin Williams' widow Susan talked about his heartbreaking final few months before death

The couple were told by doctors to sleep in separate beds as Robin struggled with insomnia.

She said: "He said to me, 'Does this mean we're separated?'

"That was a really shocking moment. When your best friend, your partner, your love - you realise that there's a giant chasm somewhere, and you can't see where it is but that's just not based in reality.

"That was a hard moment."

The couple were told by doctors to sleep in separate beds as Robin struggled with insomnia

Speaking about her husband, Susan said: "This was a man who was incredibly rich and deep and versed in so much about humanity and culture, and his humour was like this secret weapon.

"There were so many times when he would see someone needed a lift, and then he would just inject a little bit of humour in just the right way to make a difference."

The comedy actor battled Lewy body dementia before he took his own life in 2014

Lewy body dementia is the second-most common type of progressive dementia after Alzheimer's disease.

Robin had been misdiagnosed by doctors, and it wasn't until years after his tragic death that his loved ones found out what he was actually battling.

Susan continued: "Robin and I knew there was so much more going on. Robin was right when he said to me, 'I just want to reboot my brain.'

"In that moment, I promised him that we would get to the bottom of this. I just didn't know that would be after he passed."