Myleene Klass feared she would "be a single mum forever".
The 42-year-old star - who has Ava, 12, and Hero, nine, with ex-husband Graham Quinn and 11-month-old son Apollo, with partner Simon Motson - admitted expanding their family has been a "massive" change for everyone.
Speaking to Sophie-Ellis Bextor on the 'Spinning Plates' podcast, she said: "This is new for all of us, there's been massive changes in my life. I thought I was going to be a single mum forever.
"The first shock of being a single mum was horrible. It's not a blueprint I recognised, when I got into the role of a single mum, I had the fear of, 'How am I ever not going to be a single mum?' I really like how this flows.
"I really love me and my girls, it feels like it's us against the world. I love that we go everywhere together, I love that they're my three amigos, it's a really lovely feeling."
Myleene - who met Simon in 2015 and celebrated four years with her man in October - admitted she found it "terrifying" dating as a single parent.
She explained: "Everyone says, 'Dating when you've got children must be fun', and it's terrifying. It's absolutely terrifying.
"You've got a crepey belly now and keep looking at your phone on the date in case there's something wrong with the kids.
"There's nothing hot and sexy about dating when you're a mum. Everyone says, 'You must feel like you again, it's your time'. As a mum, you never feel like you as you've got dependence. The novelty [of dating] wore off very quickly."
Myleene even insisted on vetting Simon first, and she wanted to make sure he wasn't the kind of person to leave his family.
She added: "As soon as I found out he had a family, I refused to meet him until someone could give me a backstory.
"I wouldn't meet him, so he rang me and that was our conversation. I wanted to know that he hadn't had an affair. He had actually been on the receiving end of an affair. I thought, 'That's nice, I will meet you.' "