Kaye Vassell, who is the mother of the N-Dubz star's two children, claimed to Heat that the saucy snap - which shows Dappy completely naked apart from a baseball cap and shades - has not been digitally altered.
Vassell told the publication: "It's 100% real. I should know - I took it on my phone in my room! And I'm the one who put it on the internet."
"He wanted me to leak the photo of him, because, you know, people had leaked pictures ofChris Brown and Aston [Merrygold] from JLS and they both had little winkle-pops, so he just felt he had to prove a point."
She added: "People thought it was Photoshopped. They were saying that no way was his ding-dong that big. But why do you think I've stayed with him for so long? He thinks it's really funny that you're asking me about his willy!"
Dappy himself also previously confirmed that he had decided to leak the nude snap, telling The Mirror: "I saw Chris Brown had done a naked picture and he has a teeny-weeny little thing. So I thought to myself, 'I can do that too, man and mine ain't tiny'."