Jennifer and Ben started dating in 2002, but called their relationship off days before they were due to get married two years later.
"It felt like my heart had been torn out of my chest," the 45-year-old confesses in True Love. "And when the realisation that I wasn't going to have the fairytale family I wanted really set in, well, that was when I really started to fall apart."
It was then that Marc walked back into her life. They had first been introduced in 1998 backstage at a Broadway production, when the first thing Marc said to the singer was, "One day you're going to be my wife".
Five months after her split from Ben, Jennifer became Marc's bride. "He was warm and funny, a brilliant singer who knew how to make me feel special," she writes. "He was so sure of everything, and at this moment, when I felt so lost, so broken and alone, there he was."
Jennifer hoped she had found her fairytale ending, but it wasn't to be.
"Things between Marc and me weren't perfect," she admits. "Our marriage was never the kind to glide along peacefully. From the beginning it was tumultuous, passionate and explosive."
The couple worked hard to keep their marriage on track, but seven years after tying the knot, they knew it was over.
"My own happiness and sense of self-worth depended on how happy he was. So when Marc stated so clearly he wasn't happy, it broke me down completely."
Happily, Jennifer has finally found a new beginning, and is now focusing on her children, her career, and herself.
Asked about news of Marc's engagement to model Shannon De Lima, 26, this week, she said, "I'm happy for him" as she revealed she was working to get herself ready for the right person.
"It's not going to be forever," she told Today show host Hoda Kotb. "Someone great will come along."