"My mum thought I'd lost my mind," says Kate Ferdinand. The wife of former England and Manchester United defender, Rio, is discussing how her family first reacted to the news that she was dating an older man with three kids who had recently lost his first wife, Rebecca, to cancer.

That was 2017 - around the time Rio's BBC documentary about adapting to life as a single parent was broadcast. It was watched by more than seven million people.

He was used to getting stopped for selfies by sports fans, suddenly he was being hugged in the street by strangers.

Rio found filming it tough but says it really helped him. "I was broken before. I felt like I wasn't going to get out of that hole… Then I met Kate and everything changed."

Kate is 27 and 12 years younger than Rio. She admits that she was a "bit naive," about what life would be like as a stepmum to his three kids - Tia, 8, Tate, 11 and Lorenz, 13. "Then I came into the family and I thought, woah, it's going to be fine - but it's a lot of hard work."

In person, Kate is warm and chatty. She does most of the talking, at times stopping Rio going off topic. It's not surprising that Rio's dad, Julian, describes her as "strong-minded" in the programme.

'Our relationship moved faster'

About six months after they met, Rio's mum, Janice, also died of cancer adding to the family's grief and the emotional challenge facing Kate. She says the sense of responsibility to look after the kids meant their relationship "moved faster" than average.

Now, the loved-up pair who got married in Turkey last September - have teamed up to make a new film about the struggles of being a stepfamily.

"I was a bit nervous," she admits. "During filming, I had bad days and didn't want to film because it brought up a lot of emotion. But once we were in it, I really saw the effects. I hope people will relate to it and it can help them too."

According to data from the Office of National Statistics, about one in 10 families in England and Wales are stepfamilies.

But Dr Lisa Doodson who runs Happy Steps, an organisation offering support to stepfamilies, believes this figure is an under-estimate.

She claims this is for several reasons including the fact that kids can only be associated with one household so if mum and dad both go on to have new relationships the children will only be "counted once".

'I was used to just looking after me'

Before meeting Rio through friends on holiday in Dubai, Kate was living a very different life as a reality TV star on The Only Way is Essex.

"I was used to just looking after me," she says.

"I didn't really cook. I just went out for dinner or to my mum's. Looking after three kids and worrying about them before myself was something I've never done before."

Image caption Kate and Rio encouraged the kids to go to grief counselling

Her role on Towie gave her an idea of what life in the spotlight was like, but it was nothing compared to the scrutiny she would face when news of her relationship with Rio hit the headlines in early 2017.

Describing the online backlash the couple experienced, he sounds hurt. "When you see comments on social media like 'oh he's moved on a bit quick' you think 'well, ok, but I hope you don't have to go through this type of situation'".

'People had a right to judge me'

Kate is more philosophical, especially when it comes to family and friends' reactions. "I was involved in a lot of drama on Towie with my ex [Dan Edgar]. People are probably within their rights to judge me. You would be worried about the new person coming in [to the family] and think - is she the right role model for the children?"

There's been some online chat recently about the fact that stepmums get a bad name in books and films, sparked by a tweet on the subject by presenter Fearne Cotton who is also a stepmum.

Kate agrees that it's time to rethink how stepmums are portrayed. "Tia and I were watching a film the other day with an evil stepmum in it and I said 'I'm not that horrible, am I?'"

She laughs but then gets serious. "Stepmums are always evil - you never see a film with a nice stepmum - we've got that title. But hopefully that can start to change."

It seems clear that Kate has helped Rio and his kids move forward. She quit her job and spent time bonding with them, a period she says was a bit like her "maternity leave".

The kids all played big roles in their wedding and the doc shows them sharing emotional moments at their mum and gran's graves on Mother's Day.

Image caption Kate is more confident now in her role as stepmum

Most of Kate's mates are in their twenties and either don't have kids yet or have just had babies, so it ended up being Rebecca's best friend, Lisa, who helped her find her feet.

"She helped me through a lot, I don't think I'd be half the stepmum I am without her."

After everything their family has been through, Kate and Rio both agree that the five of them are genuinely in a "good place".

Rio says his oldest son, Lorenz, sums it up best: "He says it's a 'brighter house' since Kate came - listening to the kids warms my heart because I know we've made the right decision".

Rio and Kate: Becoming a Stepfamily airs on Monday at 9pm on BBC One.

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