The Celebrity Big Brother winner started dating the Spurs footballer in October last year, but their romance hit the rocks last month amid allegations that Defoe had been unfaithful.
"Expensive shoes don't make you happy, they really don't," Houghton told the News Of The World.
"Most of these WAGs used to have nothing and now have their expensive bags, tans and outfits. But those things don't mean a thing when your boyfriend's cheating on you.
"One day they'll wake up as a 40-year-old and think: 'I've got a whole house of Louboutins and Jimmy Choos but I'm not happy'."
Discussing the reasons for the break-up, Houghton confirmed that she was left heartbroken when she spotted a picture of another girl on Defoe's mobile phone.
She added: "You can't buy happiness. People stand by their man through the cheating just so their lifestyle doesn't change. I wasn't prepared to do that."
Houghton married Ordinary Boys star Samuel Preston in August 2006, but the couple announced that they were divorcing ten months later.