Britney Spears is said to be thrilled about becoming a "stepmother" after the arrival of her fiance's second baby. Kevin Federline's ex-girlfriend Shar Jackson gave birth to a baby boy in a Los Angeles hospital. They already have a two-year-old daughter. Shar was five months pregnant when Kevin dumped her for Britney but insists she bears her no ill. The pop princess dashed out to buy a bouquet of congratulatory flowers as soon as she heard the news. Meanwhile, ex-husband Jason Alexander, to whom she was married for just 55 hours, has signed a book deal. He is planning to reveal all about their relationship and their Las Vegas nuptials.