A Silicon Valley venture capitalist is at the center of a disturbing lawsuit.

Michael Goguen, a now former managing partner at Sequoia Capital, has been accused of "sexually, physically and emotionally" abusing a woman for 12 years.

For his part, Goguen said in a LinkedIn post Saturday that he's being extorted after their relationship went "sour."

According to the lawsuit, filed on March 8 in San Mateo, Goguen met the woman -- Amber Laurel Baptiste -- in 2001 at a Texas strip club. Baptiste had been a victim of human trafficking since the age of 15, according to the suit.

Goguen had promised to help her break free, according to the court document, but their arrangement became a form of sex slavery in and of itself. She submitted to "countless hours of forced sodomy, verbal abuse, demeaning rituals requiring her to beg Mr. Goguen to masturbate on her," among other details included in the filing.

In 2012, Goguen promised to pay for Baptiste's expenses, according to the suit. But in mid 2013, he stopped. Baptiste hired a lawyer -- whom she subsequently dropped. Goguen promised to pay her $40 million -- in $10 million increments -- for abuse endured and for allegedly infecting her with HPV.

Goguen paid Baptiste $10 million but refused to pay the remaining increments, which is why the suit is now in court -- and is filed as a breach of contract complaint.

Goguen said he plans to file a "cross complaint" on Monday, according to his post on LinkedIn. He said it will showcase how Baptiste -- a former lover -- is now extorting him. He vowed to include an "enormous amount of evidence, including Ms. Baptiste's emails and text messages that span many years."

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News of the lawsuit was surfaced by TechCrunch on Friday. Sequoia tweeted on Friday evening that it has let Goguen go.

"We understand the allegations about Michael Goguen are unproven and unrelated to Sequoia. Still, we decided his departure was appropriate."

Goguen, whose partner page on Sequoia's website now goes to an error, had been with the firm since 1996, focusing on the energy and security sectors and sitting on the board of more than a dozen companies.

As a firm, Sequoia caught flak in December 2015 when chairman Michael Moritz gave a less than stellar explanation for why his firm doesn't have any female partners. Sequoia is "not prepared to lower our standards" to get more women in the door, Moritz said.

Correction: This story has been updated to reflect that Baptiste was not a minor when she first met Goguen.