"The claims asserted in the complaint reflect an understandably emotional response to a devastating personal loss, but they are not actionable under the law," the airline said.
Madden's attorney, Dan Mastromarco of The Mastromarco Firm, said he is preparing a legal response.
Madden became a Southwest flight attendant at age 64 after several other careers, including real estate and paralegal services.
"I've worn seven hats in my life," she said. "This was my dream."
The New York native said she was able to chase her dream because her husband was retired and took care of everything at home and shuttled her to and from the airport. The pair met when she was 12 and he was 17 and were married for 35 years.
"He was a phenomenal man. He had a heart of gold," she said. "There is nothing and no one that can replace him."
The Federal Aviation Administration requires recurrent training for flight attendants, and Madden said she was initially signed up for April 2020. It was moved to mid-July due to the onset of the pandemic.
Southwest flight attendants and instructors were not screened for COVID symptoms prior to or during the day-long training or asked about COVID exposure, according to the lawsuit.
Masks were required, but there was no hand sanitizer supplied, and equipment from fire extinguishers to megaphones wasn't sanitized between uses, the lawsuit says.