The widow of money manager Seth Tobias was having an affair with her personal trainer at the time of Tobias' mysterious drowning death, claims one of the couple's former employees. Former assistant Bill Ash - who has told police that Seth's widow, Filomena, plotted to murder her husband - says she had been seeing celebrity fitness guru Doug Caporrino for months before Seth's death last September. Seth, who was 44, and Filomena, 41, had "an under-standing in which they could see other people on the side, so long as Filomena didn't embarrass him in public," Ash tells us. But Ash contends the CNBC commentator was threatening to divorce her. In February 2006, the couple got into a heated argument when Seth found her dining with another man at a Palm Beach restaurant, according to a police affidavit. "Filomena and Seth were screaming obscenities at each other," local TV station WPBF station reported, citing an arrest affidavit. Police busted Filomena after she slapped Seth, who had "accused his wife of sleeping around," the station reported. Filomena later told police she was defending herself, the station reported. In the police report, Filomena accused Seth of using cocaine and claimed he regularly beat her, the station reported. Shortly after the incident, Ash says, Filomena "turned for comfort" to trainer Caporrino, whose clients have included Sylvester Stallone, John Travolta and Eddie Murphy. Caporrino also appears on "Live With Regis and Kelly." "She was taking him to parties," says Ash. "I asked her if they were having sex. She hemmed and hawed and said, 'It's on a spiritual and emotional level.'" In an April 27, 2007, e-mail that Ash says Caporrino sent Filomena, the trainer - shown above with Filomena in a photo sent to us by Ash - writes: "It's so funny that there are so many feelings so quickly between us. I don't question it, only wonder why it took so long for 2 people from Hoboken to find a way into each other's lives." In a May 16, 2007, e-mail, Ash says, the trainer wrote Filomena: "You make every day of my life and every event special ... I love you, Fil." Since Seth's death, Filomena and Caporrino have remained close, spending the holidays in Aspen, according to Ash. Caporrino didn't respond to calls and e-mails from us Thursday. "We deny everything that comes out of Mr. Ash's mouth," said her attorney, Gary Dunkel. Meanwhile, a Palm Beach County judge delayed the trial over Seth's fortune while his brothers, who also claim Filomena killed him, gather evidence http://nymag.com/news/features/43914/ She killed him!!!!!!!!!!!!!!!!