The reality star took to Twitter to discuss the woman, who claims to have slept with one of Osbourne's ex-boyfriends.
The unnamed female has also sent graphic drawings of herself to Ozzy Osbourne.
"I have #SingelWhiteFemale from spain I think U crossed the line when U f**ked my X & R now drawing pics of U w**king 2 my dad #MMURPsycho (sic)," she tweeted.
The 27-year-old is yet to reveal the identity of the woman. Osbourne split from Luke Worrall in July 2010 after he cheated on her with transsexual model Elle Schneider.
She is now dating Matthew Mosshart - the brother of The Kills musician Alison Mosshart.
"Matthew is the first guy Kelly has ever brought home that every single one of her friends and family like. And he's also the first boyfriend with whom she's had a close relationship with his family," a source said.