Is V. Stiviano Donald Sterling's Girlfriend?

So much for V. Stiviano's claims she was NEVER Donald Sterling's girlfriend ... her own court documents say she was a prop to show off the Clippers owner's "sexual prowess."

TMZ broke the story, Stiviano has been denying she was ever Sterling's girlfriend -- telling people she was simply his "archivist" for years and things never progressed beyond work-related interactions.

But Stiviano says the opposite in new court docs -- claiming she's been Sterling's sexy sidepiece for 4 years, much to the mortification of Sterling's wife Shelly.

The documents -- filed this month in connection with Shelly's lawsuit against V. claiming she duped Donald into showering her with more than $2 mil in gifts -- say the relationship between V. and Donald was "neither [a] hidden, closeted, nor a clandestine 'affair' at any time," adding it was "open notorious, obvious and long standing."

The documents never use the term "girlfriend" or "boyfriend" to characterize the relationship and it doesn't say they had sex. But it sure is coy.