T.J. Arriaga loved Phaedra. For the 40-year-old musician, their late-night online chats were a salve for his loneliness. They talked about the heartache Arriaga felt after his divorce. They planned a trip to Cuba. They had steamy online encounters. “It’s true. I’m a naughty person,” Phaedra wrote, including an image resembling a woman in pink underwear.