Pop star Janet Jackson's hidden husband of nine years -- who was generally labeled her boyfriend -- made their "secret" marriage public yesterday when he filed for divorce in a Los Angeles courtroom. "We decided early on that we wanted to keep our private life private," Rene Elizondo, 37, who wrote more than 30 of Jackson's songs and directed several of her videos, told Reuters. "I'm as surprised as you are that we managed to keep it a secret." Jackson, 34, the younger sister of Michael Jackson, released a statement saying that she had "tried to keep my marriage private in an effort to have a normal family life." The couple separated last year after living together since 1986 and marrying in 1991, said Elizondo, whose lawyer told Reuters that he is intending to challenge certain aspects of the couple's prenuptial agreement, given that Rene was "instrumental in her career."