The actor, who played factory boss Mike Baldwin, felt like a failure following the end of his 29-year relationship with wife Christine.
"For an instant I wanted to end the pain forever," he told The People. "I was on my own in my ninth floor flat and felt I had failed as a husband and parent. I thought, Oh My God, all the years I've worked and things have come to this. I was really low and believed jumping out of the window would end my suffering.
"It has been utter, utter hell and the feeling of despair had been dragging on so long I believed this is it, I can't go on."
Johnny and Christine have four children together, Jennie, 27, Michael, 25, Stephanie, 22, and Anthony, 16.
He added: "The children have been supportive but are very unhappy that we are divorcing. They don't want us to talk to them about the split. I feel very sorry that Christine wants to go through a divorce. I don't know the reasons - you'll have to ask her."