The 39-year-old actress has 10-year-old Birdie and five-year-old Cricket with the producer - whom she married in 2007 - but says that when her love life hit a rough patch, she sought emotional support in the arms of another man, and considered getting a divorce.
Writing in her new memoir 'This Will Only Hurt a Little', Busy said: ''There was a man I was friends with, another dad. We'd been having lunch and stuff. Texting. Talking on the phone a lot. Honestly, I had a crush on him. I like him. Maybe I even loved him? He clearly liked me too.''
Busy says she confronted Marc and told him she wanted a divorce, to which he asked her for another chance.
And when thinking about her options, she says her best friend Michelle Williams urged her to try and ''keep her family intact''.
Recalling the advice Michelle - who has 12-year-old daughter Matilda with former boyfriend Heath Ledger, who passed away just months after they split - gave her, Busy wrote in her book: ''[Michelle said] It would be really awful for two years and then you would find a new normal but honestly, if you can keep your family intact, I think you should do it.''
The former 'Dawson's Creek' star also sought the opinion of a therapist, who told her: ''Listen. Divorce f***s up children. It just does.''
Busy and Marc later started attending therapy separately to work on their issues, and are still together today.
She wrote: ''This time, Marc got his own therapist. And we started to work through it. But I also kept talking to my emotional boyfriend (for lack of a better term). I know. That part is so s**t. I'm sorry. I really am. I really truly am.''
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