Joe Mixon told police "it felt like a dude hit me" when he was slapped by a female student in 2014 ... and that's why he hit back.
Officials have released video of Mixon's interview with police investigators, shot in 2014, in which the Oklahoma football star tells his side of the story.
Mixon says the whole thing began that night when the female student blew smoke in his face and he went to confront her about being "disrespectful."
Mixon says a male member of the woman's group, who he believes to be gay, called him a "n**ger.