The pair were both members of N-Dubz along with Contostavlos's ex-boyfriend Fazer, until the group confirmed their split earlier this year.
"We always have little arguments, but she knows I love her deeply and I'm really protective of her," Dappy is quoted as saying in The Sun.
Dappy explained that he would like to "catch" MC Ultra, an ex-boyfriend of Contostavlos who leaked a sex tape featuring the X Factor judge.
"I can't wait to catch that guy, MC Ultra, who sold that sex tape. He was her boyfriend for four years. They decided to do something nice together and keep it on the phone, for themselves. He's an idiot," he explained.
"She left him because he was a right softie and she wanted a real man. I remember the day - he was crying like a little baby when we were on tour."
Dappy added: "A year later he sold the tape and got his little pay cheque. So well done."
Dappy was arrested back in April following a brawl outside a petrol station that left three men with facial injuries.
He denies allegations of affray made against him and the case has been adjourned until July 19.