She reached the final of the 2013 edition of the show alongside Brendan Cole, eventually finishing fourth overall.
She said he “became unusually insistent on knowing where I was all the time”.
“If I didn’t reply to a text, he’d spiral,” she added.
“Supporting me in all that I do usually came so easily to him, but with Strictly I think he was just waiting for it to end,” Ellis-Bextor said.
“He’d message me all day when I was rehearsing, extra keen to know my schedule.
“We would argue when I was home about how distracted I was and about whether I’d get through to the next week.
“He just felt as if I might slip into a new life that left our family behind.
“I had no such desire, but was too spent at the end of the day to give the reassurance he needed. I think the only real reassurance could come with the show finishing.”
Ellis-Bextor, who has five children with Jones, said there was a “slight weirdness in forming a new ‘couple’ when you’re both two married strangers”.
“Why do they fetishise the ‘couples’ aspect so much? Dance partners, yes, but a couple has a different nod.”
She said Jones “began seeing a counsellor after I’d been in the show a month or so, and it really helped”.
“Perhaps I should have, too,” she said.
“We never doubted our love for each other but I think Richard worried that I just wouldn’t want our life again,” Ellis-Bextor added.
“But of course I did. To me, my family is everything.”
Ellis-Bextor described Cole as a “complete gentleman throughout”, adding: “I’m glad I did it and dancing the Charleston is one of my favourite things I’ve ever done, and thank you to Brendan for making the whole show lots of fun.
“We never argued and I’m proud of that, but I’m prouder still I didn’t cry or anything.
“I kept part of myself back and no matter what I was asked to do, I never did more than I meant. It took more strength than you’ll know but hey, it’s just a nice thing I did once.”