MADRID, Spain—Lionel Messi began crying before he even started speaking. The “most difficult” moment of his career had arrived and he wasn’t ready for it. It was time to say goodbye to Barcelona after more than two decades with the Catalan club. “I don’t know if I’ll be able to speak,” he said while trying to compose himself during his farewell news conference at the Camp Nou Stadium on Sunday. “It still hasn’t sunk in that I’m leaving this club, that my life will be changing completely. It will be a difficult change for me and especially for my family. But we have to accept it and move on.” Messi struggled to control his emotions and cried profusely as he stepped up to the podium at the Camp Nou. “This is very hard for me after so many years, after being here my entire life,” he said. “I wasn’t prepared.” …