Speaking to TMZ, the singer was initially fairly civil when describing their break-up and pending divorce, insisting that he had their children's best interests at heart.
"That's what happens when two people separate," he told photographers outside a US airport. "They move on and that generally means other people in their lives.
"I don't expect Heidi to all of a sudden become a nun [and] as always, my main priority is the emotional well-being of our children."
However, he said of Klum's alleged relationship with her bodyguard Martin Kirsten: "If there is going to be someone else in their lives, I'd much rather it was a familiar face.
"I guess the only thing I would have preferred is... while I didn't expect any better from him, I would have thought Heidi would have showed a little bit more class.
"[She could have] at least waited until we separated first before deciding to fornicate with the help, as it were."
Seal went on to suggest that Klum's relationship with her bodyguard - which was recently described as "complicated" - could have been the reason that the pair split.
"I guess you all now have the answer that you have been looking for for the past seven months," he cryptically told reporters, before leaving in his car.
Seal and Klum filed for divorce in April this year, but proceedings have reportedly "hit a snag" over assets and matters relating to their children. Seal is currently taking a break from recording and is due to return as a judge on The Voice Australia next year.