The 34-year-old presenter opened up about the moment her partner of 11 years and father of her two children walked out of their family home in an interview with the Mail on Sunday's You magazine.
"You see, I thought [Graham] and I were so happy," she said. "I had just walked down the aisle, so of course I didn't see it coming - I hadn't even got my wedding dress back from the cleaners.
"When it first happened and I was in the middle of the storm I was just so very, very hurt. I felt I would sooner have taken a bullet. Actually, at the beginning, every morning when I woke up, I thought I had taken a bullet to my heart.
"It's so unfair that people call it 'heartbreak' because that word almost romanticises something that is beyond pain. It is all-consuming, it is debilitating because you cannot move - cannot do or think of anything else for the sake of a wound that you cannot see, that no-one can see."
When asked whether she immediately resented Quinn for his actions, Klass revealed that it took her a while to accept what had happened.
"Everyone around me kept urging me on by saying to me that the bad things that happen to you in life make you stronger," she said.
"I remember one day asking a friend, 'How strong do I have to be? Like kryptonite?' And she said, 'No, you have to be like bamboo - be malleable, keep on bending but still be strong'.
"My friends were like my backbone when I didn't feel I had one. I am so appreciative that they all let me talk, talk, talk. Not once did any of them say 'Stop talking about it' or 'Stop crying'.
"Your love for someone isn't a tap. You can't switch it on and off. It doesn't matter who you are or what reasons they give for leaving you - it doesn't matter if they run off to join a circus or if they run off with Cindy Crawford. It hurts."
She added: "There were days when I didn't want to get out of bed and my mum would say to me, 'It's OK, you are just grieving'. And she was right - it is a kind of grief, a grief that you have to work through."
Klass revealed that despite the shock caused by her husband's decision, she was determined not to give up for the sake of her daughters Ava, 5, and Hero, 18 months.
"I withdrew, I couldn't grieve in public," she said. "I didn't fall apart because I knew that above everything else the children needed me to be strong for them. So I did the school run as usual... and then I went home and packed.
"I drove for about a mile and just stopped the car, turned around and looked at the girls, and I thought, 'I have everything I need; I have got it all here'.
"It was a good lesson in the sense that I think you can lose sight of what you have. The children have been my absolute salvation."
Klass recently designed a range of clothes and lingerie for Littlewoods and a collection of children's shoes for Start-Rite. She admitted that she still has good days and bad days.
"I don't know what's going on with [Graham]," she said. "I can't speak for him.
"I can only speak for myself and all I can say is that it has been the hardest six months of my life."