Seal told TMZ about one week ago Klum was cheating on him with her bodyguard, Martin Kristen, before they separated in January.
"I preferred Heidi would have showed a little bit more class and at least waited until we separated first before deciding to fornicate with the help," he said.
In an interview with Katie Couric on the show "Katie," Klum said Seal's suggestion she cheated on him was devastating, the New York Post reported.
"It was a unique choice of words ... I'm used to it. Other people aren't. When we were together, I never looked at another man."
Witnesses spotted Klum with Kristen while she was on a family vacation in Sardinia, Italy last week, People magazine reported. The sighting sparked rumors the two are dating, but Klum's friend, whose name was not reported, said they're not.
"It's complicated," the friend told People. "Their relationship is hard to define.
"This has been a difficult time. Her inner circle of people she trusts is getting smaller and smaller and he is her No. 1 confidante," the friend said of Kristen.
Klum and Seal filed for divorce in April.