The show must go on may be an old showbiz slogan, but Liza Minnelli took it to a new level with an appearance and performance last weekend in Miami Beachthe same day she learned that an ex-husband had died. On Saturday night, Minnelli brought out a large crowd of well-to-do gays and straights to Miami Beachs Sheraton Hotel, Bal Harbor, to raise money for Center One, South Floridas oldest AIDS services organization. The crowd included Hollywood legend Mickey Rooney (onetime on-screen partner to Minnellis mother, gay icon Judy Garland) as well as South Beach resident and star Jon Secada; all those attending dined on the same menu eaten by the king and queen of Spain a few weeks earlier at another function in Miami Beach. Minnelli has been a longtime supporter of AIDS charities, in part because of the deep impact the disease has had on her own life: her first husband, singer and actor Peter Allen, succumbed to AIDS complications several years ago. Minnelli showed up with a cane despite having undergone a second hip replacement just a couple of weeks earlier. Earlier in the day she had reportedly learned that another ex-husband, with whom she was on cordial terms, producer Jack Haley Jr., creator of Thats Entertainment (and son of Garlands Wizard of Oz costar Tinman Jack Haley), had himself died of respiratory failure late last week. After accepting Center Ones Red Ribbon Award for her services to the AIDS community, Minnelli surprised the audience by giving an impromptu performance and singing publicly for the first time in over a year.