Uchitel also says published text messages she allegedly exchanged with Boreanaz are "not authentic" and were leaked to portray her in a negative light.
Boreanaz, 40, told the magazine he was speaking out because a former lover has contacted an attorney and threatened to spill secrets to the media.
"I was associated with a woman who I was involved with and had a relationship with," he says. "She asked for money. I felt as though I was being blackmailed or there was some sort of extortion," he told People.
Boreanaz declined to say who the woman in question was.
Back in October 2009, Star Magazine reported that the Bones star was cheating with Rachel Uchitel, the infamous alleged mistress of Tiger Woods.
Now, Rachel Uchitel has come forward, along with her attorney Gloria Allred, saying she had an affair with Boreanaz and discrediting newly released text messages she supposedly exchanged with Boreanaz.
"Rachel Uchitel had a romantic relationship with David Boreanaz," Allred says.
The statement continues:
"She understood that he was unhappy in his marriage and had been for some time and she had reason to believe that he intended to separate from his wife. He continually asked Ms. Uchitel to be patient and to wait for him. Some of the reasons that she believed him include that he spoke to Ms. Uchitel on the telephone and through text messages from morning until night on a regular basis. He treated her as his girlfriend and also took her out in public. He called her between takes when he was taping his television show and put her on the telephone with his friends and his son. He even stayed with Ms. Uchitel when he came to New York for press tours. He gave her a silver key on a chain to symbolize 'the key to their hearts.' He also sent her a video of himself telling her how much he loved her, that he loved her then and that he would love her forever."
Allred says Uchitel still has that video.
She also claims Uchitel broke off the relationship because she felt Boreanaz "had not been completely truthful with her, and she no longer trusted him."
In her statement, Uchitel strikes back at published text messages she allegedly exchanged with Boreanaz, which she says were "taken out of context or incomplete."
The alleged texts, obtained by Radar Online, begin with Uchitel telling Boreanaz they don't spend enough time together, and continue:
Uchitel: "Just (bleeping) go and be with her."
Boreanaz: "Why do u act like such a (bleeping) child!!! She is my wife."
Uchitel: "Oh, please!! ... You're such a liar. You're never leaving. You've wasted my time and I'm once again alone." She adds: "I can't (bleeping) be alone anymore. I've been alone my entire life."
Boreanaz: "What the HELL are you talking about. We spend more than enough time together."
In her statement Thursday, Uchitel says of the texts, "For reasons unknown to me I believe that someone is deliberately trying to portray me in a false light. These texts should not have been published. I am in possession of many authentic text messages between David and myself which portray a completely different picture than the one based upon the texts that have been published today."
She also claims that "...the authentic texts which I have reveal that David Boreanaz repeatedly expressed his deep love and affection towards me."
Uchitel concludes, "I am deeply hurt and offended that anyone would think that I wanted to break up his family. Nothing could be further from the truth."
She also says she broke off the relationship because she no longer trusted or respected the actor.
Boreanaz has said he is now trying to mend his relationship with his wife.
The couple has been married for nearly nine years.