She tells the British magazine Saga that early in their relationship Stewart indicated that he didn't want more children, which is something she wasn't OK with. In fact, she says she would have left the rocker if he hadn't changed his mind.
Penny is out promoting her new memoir, Someone Like Me, which drops Thursday. Stewart shared his ringing endorsement of the book in an Instagram video: "Wow, this is incredible, Penny, absolutely blood curdling information here," he says, before pointing to a specific page. "You shouldn't have put that in the book, Penny."