However, he said that he still remembered why they split up and was surprised at Chantelle's continued feelings for him.
As he joined Davina on stage and watched his best bits, the former Celebrity Big Brother 4 housemate said: "I'd forgotten about half of that. It's really great to see that."
When Davina asked how it felt to leave the house, he said: "The calm that's going on in there now, everyone's talking about other stuff. And then you walk up the stairs and, 'Waaaaaah!' Suddenly it's the world you try and forget about when you're in there."
Moving on to what it was like to re-enter the house with ex-wife Chantelle, Preston said: "I think it's rare for people who are divorced to be in the situation where you spend a lot of time with each other."
The sound cut momentarily, as Davina apologised for Preston's swearing. He said sorry before adding: "[Chantelle]'s a flipping great girl."
He continued: "I still remember why we split up, but I remembered all those things I'd forgotten about during those times. Because it wasn't just a glossy magazine break-up, it was really dark, for both of us. But we've moved on. I think we've matured in different directions anyway."
Davina then showed the Ordinary Boys frontman a video of Chantelle's comments about their relationship in the house. Looking sombre, he seemed surprised at Chantelle's continued feelings for him, saying: "I've only been a phone call away this whole time [since the divorce]. She could have just talked to me."
He added: "We'll talk tonight and she can say whatever she couldn't say in there."
"Did you not pick [her feelings] up?" Davina asked, to which Preston laughed: "I don't know!" Davina then jokingly dismissed him, saying: "You guys are pants!"
Moving on to his housemates, Preston said that Brian was "fantastic", before saying of Nick: "I kinda had a feeling Nick was going in, and I thought he would be this sly guy, I'd have to try and avoid him. But he's probably my best friend in there.
"I'd already converted him to 'Naughty' Nick in the first week, and I think he's reached 'Nice' Nick now."
Asked who he would like to win the Ultimate Big Brother crown, Preston replied: "Nick!" to a murmur of booing from the crowd.
Reflecting on the end of Big Brother: "I was always really aware of the fact that it was something that defined me. But now, I don't see that as a problem. It's been a massive part of my life.
"I think it's really sad that it's got to end."