Ex-NFL star Kordell Stewart is going after the blogger he claims snatched a nude video and posted it online.

Kordell's suing Quentin Latham for a December 2016 post that included video of Stewart's exposed junk and ass. In the docs, obtained by TMZ Sports, Kordell also accuses Latham of creating a fake email account ... which he used to make it seem like the video had been exchanged between Kordell and another man.

Kordell's lawsuit repeats what he told TMZ Sports ... "at all times during his life, Mr. Stewart has been, and is, a heterosexual male." According to the docs, Latham also posted a story claiming Kordell intended to marry Tyler Perry.

As we first reported ...  Kordell initially claimed his ex, Porsha Williams from 'Real Housewives,' had jacked the video from him and submitted it to the blog.