"I felt like I had broken his trust with that information getting out. The thing I was most disappointed in was that it had an immediate effect on my relationship with Justin," Nielsen said.
Langer was upset that his secret dossier sent to Nielsen before the start of the Ashes, describing England cricketers as "lazy", "shallow" and "flat", was leaked to the media earlier this month.
Nielsen, however, said it is normal to have such a note on opposition.
"It is not so much the information. Every team and every player has dossiers about them and about other players and ideas," he was quoted as saying in the media.
"I'm sure they (England) are saying the same thing about our players or probably even me. The biggest issue for me was the personal issue I had to deal with Justin."
Nielsen also said Australia are not devoid of knowledge regarding English players.
"You've got to remember we've got a guy called (Ricky) Ponting who'd played against a few of these English players both in England and Australia in the past. We didn't come here with no experience or no understanding of how they would go about it," he said.