The singer posted a message on Twitter last month to "absolutely deny" allegations of a fling.
© WENN
© Rex Features
She later received death threats for the remarks and was criticised by PR guru Max Clifford for bringing the little-heard rumours into the public domain.
Jenkins defended her actions last week and has now added to Heat: "I think I did the right thing.
"I had to stand up for myself and I felt like I needed to do it. Everyone's been so positive and supportive."
The magazine has claimed that Jenkins has stopped wearing dresses from David's wife Victoria's fashion ranges since the incident.
"After Victoria had to deal with the embarrassment over Katherine's 'confession' that she was not having an affair with David, it's no surprise that Katherine wasn't wearing one of Victoria's latest creations [at the GQ Awards]," a supposed insider said.
"Katherine has worn Victoria's dresses at least eight times - mainly at awards ceremonies. But given the recent events, no-one could blame Posh for holding back on this occasion."
