By Lisa Richwine (Reuters) -“Aquaman” actor Amber Heard choked back tears on Wednesday as she testified that ex-husband Johnny Depp physically abused her, starting with slaps after she laughed at one of his tattoos and escalating to a “cavity search” of her body for cocaine. Heard took the witness stand for the first time in a widely followed U.S. defamation case brought by Depp, saying the actors had a “magical” relationship until it turned violent. Depp’s first physical outburst, Heard said, came after she asked what was written on one of his faded tattoos. She said he replied “Wino,” and sh…