Kordell Stewart Furious Over Stolen Naked Video ... Blames Porsha (VIDEO)

Kordell Stewart says newly surfaced video purportedly showing the ex-NFL star in the nude is real -- but it was stolen -- and he's pointing the finger at his reality star ex-wife.

TMZ Sports spoke with the former Pittsburgh Steelers QB who says he's outraged that the video went public because he had made it specifically for a woman he was dating at the time.

Stewart says he's already contacted his lawyers and plans to rain down hell on whoever released it.

Kordell says his #1 suspect is his ex-wife, Porsha Williams -- claiming she had sent him text messages warning him to "prepare for war" ... and he believes she was referring to the tape.

As for reports that Kordell had made the video for another man, the ex-NFL star tells us it's "bull****" -- and says that, while he respects gay people, that's just not who he is.