Appearing on Loose Women, Field, 36, said Williams' depression battle became so intense that, at one point, he questioned his existence.
She said: "There was a moment in his life where he thought life would end and he thought he couldn't exist any further."
But there was a light at the end of the tunnel and, with the help of those closest to him, he came out of the darkness.
Field said: "It just goes to show you that even as dark as things can seem, there is a way out and if you can start the dialogue and if you can start to shift in your mind and you have that support system - whether it’s your friends or therapists or someone that you call at Samaritans - there is a way to muddle through it and to come out the other side."
She said her husband has always been very honest about his struggles with mental health and addiction.
She added that it had taken a lot of strength to come out on top.
"I was talking about it with him last night actually and he said 'I’m not the same person I was. I'm happy. I'm married, I've got kids'," she explained.
Her appearance on the show coincides with a fortnight-long mental health campaign by Loose Women and the charity Samaritans.
The Lighten The Load campaign aims to encourage members of the public to look after their mental health by opening up on the issues they face and the things that make them anxious - from money worries to family woes.