Your teenage sister should not be so sheltered, or should not be in the coffee room.
The fact that many frum men look at/watch pornography is something that should be worked on, not something that should be hidden to the extent that when a woman catches her husband she thinks he is a freak. He just happens to be the one who got caught. Is it a problem and an issur? Unquestionably. But people are making him out to be a freak. All that does is tell someone who is struggling with this issue that they must do a better job hiding it.