The Nanny McPhee star divorced the actor in 1995, and was so affected by the break up she didn't even want to change her clothes.
But Thompson insists concentrating on penning 1995's Sense and Sensibility helped her overcome her depression, and she went on to marry actor Greg Wise.
She says, "Work saved me, and then Greg. He picked up the pieces. I was acting on stage in Me and My Girl. It was so bad that I got to the stage I wasn't really changing my clothes at home. I remember that Ken had this black cashmere dressing gown and when he was not at home I simply wore it. It was a time when I couldn't even answer the phone, yet I would go out every night to perform in the theatre and cheerfully sing the Lambeth Walk.
"To help myself, the only thing I could do was to write, but I had to crawl to the computer. Writing Sense and Sensibility saved me form going under in a very nasty way."