The male lover of Frank Batey, the homosexual who died of AIDS amid a long battle with his fundamentalist ex-wife over who would raise their young son, has won temporary custody of the youth, a source close to the case said. The source said that Craig Corbett, Batey's longtime companion, was named temporary guardian for Brian Batey, 16, in a closed hearing July 8 in San Diego County Superior Court. Brian has lived with Corbett for all but a few days since his father's death on June 26. However, he briefly disappeared early this month with his mother, Betty Lou Batey of San Diego, who had gone underground with the boy for 19 months ending in early 1984, rather than allow him to live with his father. Betty Batey's only comment was: "I love my son." She said all of her actions were taken with her son's best interests at heart.