The Chariots of Fire star 65, married Carolyn in 1974, but began an affair with model and actress Polly Williams, whom he married in 1989 after obtaining a divorce.

Nigel tells British talk show host Piers Morgan that during his affair with Polly, who died in 2004, he was so emotionally unstable that he had suicidal thoughts.

"I did not see any way of being happy," he explains. "There was not a happy way out. I got myself into such a ridiculous state ... like whatever decision I made you were never going to be happy. That is so weird isn't it? But I only have myself to blame so what can you do?"

Asked whether he had planned to kill himself, he replied, "I did not have a plan but I did think it would be a relief."

Explaining his feelings he adds, "It was either upsetting Caro (Carolyn) or upsetting Polly. That (suicide) was in the equation. It is a very dark moment and I have never really thought about it. I have never talked about this to anybody actually.

"When you are like that you have nowhere else to go and you can't talk to anyone about it. So I was in a corner but entirely of my own making."

The star was so distraught he checked himself into a mental institution, leaving after a few days after his presence was made public.

The affair attracted frenzied press interest as at the time Nigel was starring as a murderous lothario in U.K. TV series The Charmer.

He remained married to Polly and helped her battle cancer before her death in 2004. He married Georgiana Bronfman in 2007. Carolyn passed away in 2011.