At the time the tweets about Osbourne's her father and Pugh's relationship were posted, it had been rumored that Ozzy Osbourne's infidelity was the cause of his split from his then-estranged wife, Sharon.
"Kelly intentionally and maliciously harmed [Pugh] by publishing private facts and defamatory statements, in addition to inciting a rash of mass cyber-bullying against [Pugh]," the lawsuit reads. "Kelly harnessed her celebrity and notoriety to incite her followers as well as the media machine."
On May 23, the lawsuit says, Osbourne, who has more than 4 million Twitter followers, tweeted Pugh's private phone number and accused her of committing "elder abuse."
Though the tweets were eventually deleted, Pugh wrote in the lawsuit that she has "not only experienced long-lasting emotional and psychological effects of harassment and hate, but has also lost business in an amount to be determined at trial."
Earlier today, Ozzy Osbourne released a statement in which he revealed that he was in therapy for sex addiction. However, Pugh maintained that their relationship "felt like an old-fashioned romance," and told People magazine, "When I say he gave me the greatest love of my life, I mean it."
A rep for Kelly Osbourne did not immediately respond to a request for comment when asked by ABC News.