The model-turned-musician divorced the former White Stripes star - the father of her kids Scarlett, 11, and 10-year-old Henry - in 2013 but they get along well and she feels very fortunate that he is such a big part of their children's lives.
She said: ''Jack's an incredible father, he really is, an absolute class-A father.
''As ex-husbands go, I'm really lucky in that sense. As the kids get older, I realise how fortunate I am to have him as a co-parent I really give massive props to Jack in that sense.''
Though they are not together any more, the 38-year-old beauty will always keep a ''special place'' in her heart for Jack, but she admits she still has bad days over their divorce.
She said: ''I think there's no easy way around it. You can have the best intentions, and there will forever be a special place for Jack in my heart.
''But as anyone who has been through a divorce knows, there are good days and bad days. And my advice is, 'This too will pass.' I know it sounds so basic, but the truth is, whenever you are goin through anything hard, time and perspective really help.
''I want to say that I am a powerhouse of strength, but we've all been on our bathroom floor sobbing, wondering why our life is the way our life is.
''Thank God I have such a tight core of women friends. They have kept me sane in the darkest of times.''
Karen has found the separation easier as time has gone on and the main priority for both her and Jack is for their children to feel secure.
She told Red magazine: ''Jack and I have been divorced a few years now and it's a lot easier.
''We're in each other's lives with regard to our kids but we also have separate lives.
''Our kids know they are loved by their dad. They know they are loved by their mum. While it might not be ideal, it works.''
What's new in the music world this week?
'Sounds of Silence' was released on this day (January 17th) in 1966.
Listen to Alex Bayly performing 'Animal'.
Two weeks ahead of Independent Venue Week, Dry Cleaning made 'Britain's Best Small Venue 2015' (NME) the second port of call on their 2020 tour.
'Leave Home' was released on this day (January 10th) in 1977.
For their last gig of the year, The Libertines came back to their adopted hometown of Margate to finish off their latest tour.
Celebrating the birthday of David Bowie with his most legendary songs.