The pop star has just welcomed baby Amelia with his fiancée Emily MacDonagh, and has two children – Princess and Junior – with his ex wife Katie Price.
CLICK ON PHOTOS TO ENLARGE
The star says caring for Katie Price's disabled son taught him about fatherhood before his biological children were born.
But his journey into fatherhood started before any of his biological children were born – Peter has told how it was caring for Katie Price's son Harvey, which taught him everything he needed to know.
"I always say it was Harvey who taught me to be a father before I became a biological dad," says the 41-year-old of the little boy, who has disabilities. "He changed me from a boy into a man. It is something I will never forget."
Peter made the admission during a comment piece for HELLO! magazine – in which he tells how he has been inspired by families coping with disability and how he is determined to make their lives easier.
The star has been working with children's charity Caudwell – which provides support to families of seriously ill children. All being well, he and Emily will be at their annual Butterfly Ball in May.
Peter says he is so lucky that Amelia - his baby with Emily - is "just so content".
He says that when he hears other parents' stories about coping he knows how lucky he is.
"Amelia is very placid, very sweet," he says of his new baby girl. "Sometimes when we put her down to sleep she will have her eyes open for an hour or more and not make a sound. She is just so content."
For the full story – including how Princess loves to take care of her little sister – pick up the new issue of HELLO! magazine, on sale now.