Kim Porter left P. Diddy after he fathered another woman's child.
Porter, who has three children with the hip-hop star, admitted their romance imploded when she discovered Diddy had a child with a mystery woman in Atlanta.
When asked if the rumours of a secret baby were the reason Porter ended their relationship, she told Essence magazine: "That definitely was part of it."
Diddy was reportedly desperate to keep the baby a secret from Porter - who was pregnant with their twin girls at the time - and allegedly paid the unnamed mother $1 million to stay quiet.
Porter, who moved out of the music mogul's apartment in July following a 10-year on/off relationship, wanted her departure to be as "dramatic" as possible to show Diddy she was leaving for good.
She said: "I did have my little party-packing crew, yes, I did! I wanted to be dramatic. I wanted him to know I wasn't breaking up with him for two weeks or maybe leaving for two days. If I pack up everything, twins and all, it means I'M out!"
The model-and-actress, who attended Diddy's White Party in The Hamptons last week, says the rapper wasn't ready to tone down his partying lifestyle and commit to her. She revealed: "He's not ready to get married. When I get married, I want to stay married. I want both parties to be on the same page at the same time, and to leave a certain type of behaviour behind. That's a commitment I don't think he's ready for."But we have this bond, this friendship. I'M the person he can tell his inner most thoughts to, he still calls me everyday and we talk."
Porter and Diddy's eight-month-old twin daughters are called D'Lila Star and Jesse James. They also have a nine-year-old son Justin. Diddy has another son, 13-year-old Christian, from a previous relationship, while Porter has a teenage son, Quincy, with singer Al B. Sure.