Houghton broke up with the cage-fighter earlier this year and went on to describe him as "rotten to the core".
Reid has since told Now of allegations that he cheated on Houghton: "During her pregnancy I noticed a real change. She'd accuse me every week.
"I want to make it absolutely clear that, whatever I've done in my past, from the day I told Chantelle I loved her I never cheated on her."
On the infamous 'sex dungeon' claims, he said: "How can you turn an entire house into a sex dungeon? If I could do that, they'd put me on a property programme on TV.
"Since when does a couple of sex toys and some porn make a house a 'sex dungeon'? It wasn't seedy and dirty. Everything was open."
He went on to reveal details about his and his ex's sex life: "We both used to enjoy watching pornography, as any adult couple does. I don't need to justify it because it's completely normal.
"I described myself as 'try-sexual' once. But I'd say I'm a heterosexual guy who likes a bit of kinkiness. I'm obviously sexually liberated and very open-minded.
"But Chantelle knew everything before we got together. Was she the only person in this country who didn't know I was a cross-dresser?"
Although he denies ever having been part of an orgy, he said that he did 'make love with a lady while a friend made love with another lady in the same room'.
He admitted: "I've slept with prostitutes but that was a long time ago. A lot of men have done that.
"I've had a varied, fun past. I enjoyed a lot of different things."
Reid went on to say that Houghton knew about his sexual preferences, and she knew how experimental he had been - even with his ex-wife Katie Price.
"I told her I'd had a bit of a wild sex life and even went to a ping pong sex club on honeymoon with Katie," he added. "Chantelle knew that."
Read the full interview with Alex Reid in Now magazine, out now.