“I’m sorry,” said Representative Carolyn McCarthy, her voice breaking. “I’m having a really tough time.”

She’s the former nurse from Long Island who ran for Congress in 1996 as a crusader against gun violence after her husband and son were victims of a mass shooting on a commuter train. On Friday morning, McCarthy said, she began her day by giving an interview to a journalist who was writing a general story about “how victims feel when a tragedy happens.”

“And then 15 minutes later, a tragedy happens.”

McCarthy, whose husband died and son was critically wounded, is by now a practiced hand at speaking out when a deranged man with a lot of firepower runs amok. But the slaughter of 20 small children and seven adults in Connecticut left her choked up and speechless. ...........