Germany’s Alexander Zverev on Wednesday said he was ashamed of a violent tantrum following a doubles defeat in Mexico last month. “I can guarantee you I will never act this way again in my career. It was definitely the worst moment of my life, of my career, in general,” the 24-year-old star told reporters before the start of the ATP Masters event in Indian Wells, California. “If that happens again, you should ban me. But I’ll do everything I can to make sure it doesn’t happen, not only in the next year but my whole career,” Zverev said. Earlier in the week the world number three was handed a s…