The singer – who presented The Xtra Factor with Caroline for two years before they then fronted one series of The X Factor together in 2015 – said the Love Island star had left “a massive hole” after taking her own life in February.
“It still hurts every day thinking about what she must have gone through.
“When you’re grieving you’re just finding things. I had voice notes from Caroline for years.
“I had a three-year WhatsApp conversation and somehow it had been deleted.
“I’d only got the last year of our conversation and I was going through my phone looking for voice notes just wanting to hear her voice again, hear her conversation, just searching for things.”
Olly continued: “Me and Caz didn’t speak or message every day but there’s a massive hole in my life without Caz in it.
“I just miss those moments of crazy stories where we’d WhatsApp or ring each other and have the most random conversations about the most random things. I’m going to miss that forever.
“I know that goodbyes are not forever. I know I’ll see her again at some point so I look forward to that day.”
Olly also opened up about the undeniable chemistry he had with Caroline, after they were first paired up to host The Xtra Factor in 2011.
He said: “We had fights. We had great moments together. We argued. We had everything.
“We just had a special chemistry. People thought we were together. We weren’t together. We never, ever got together. We never ever pulled each other. We never did.
“We were just always like brother and sister. I don’t know, it was a weird friendship. I’ve never experienced that level of friendship before. We had a chemistry and connection.”
Olly added: “For Caz to not be here any more, it’s hard. It’s difficult.
“It doesn’t get easy but I’m just fortunate I have so many great memories with her and have so many amazing times with her that I can look back on, and I’m very fortunate a lot of it is documented and a lot of it is on TV.”
Caroline was found dead at her home in Stoke Newington, north-east London, in February this year.
She was awaiting trial after pleading not guilty to charges of assault, following a row with her boyfriend Lewis Burton in December 2019.
At an inquest into her death earlier this month, her mother said Caroline had been “seriously let down by the authorities” and was “hounded” by the press over her forthcoming trial in the weeks before she died.
A coroner later ruled her death as suicide, saying she had “no doubt” that the star intended to take her own life.