Richard Simmons revealed he's been the victim of blackmail for 'several years'

Richard Simmons is out for blood.

The 68-year-old fitness guru is alleging that his former assistant Mauro Oliveira "blackmailed, extorted and stalked" him for several years, in a jaw-dropping lawsuit against the National Enquirer and their publishers.

The lawsuit accused Oliveira -- who was not named as a defendant -- of selling false and libelous information about Simmons to the National Enquirer and Radar Online, companies owned by American Media Inc.

"Since early 2014, Mr. Simmons has taken a leave of absence from the media spotlight in order to retreat from his 40-year career in television, fitness and other arenas of entertainment. Starting from around May 2015, Mauro Oliveira, an individual who has blackmailed, extorted and stalked Mr. Simmons for several years with the intention of destroying the career and reputation of Mr. Simmons, contacted several press outlets, including the National Enquirer and Radar, and offered information on Mr. Simmons's disappearance in exchange for a fee," the court filing revealed.

The lawsuit also listed the numerous reasons Oliveira gave for Simmons' retreat from the public spotlight. His former assistant claimed that he was "frail, weak and spiritually broken." Another time, he alleged that the fitness icon was "being held hostage by his housekeeper who was controlling Mr. Simmons, taking advantage of his weak mental state and engaging in witchcraft." Lastly, Oliveira sparked rumors that Simmons was transitioning to female.

The suit continued on, claiming that the National Enquirer and Radar "knew and acted in reckless disregard for the fact that the information provided by Mr. Oliveira was false and that he was not a credible or reliable source."

However, American Media Inc. said they will continue to stand by their reporting:

"While we have not seen Mr. Simmons' complaint, we stand by our reporting about him, all of which was based on solid sourcing and material evidence. Should he choose to proceed with his lawsuit, we will defend it vigorously, and we look forward to the public vindication of our reports."

Oliveira responded to the lawsuit, revealing to People that Simmons' allegations are "false":

"The real story about Richard Simmons will come out eventually. Any reference to monetary compensation is the money Richard Simmons owes Mr. Oliveira for his work done for him, and also for the help he promised me when I stopped working for him, and also for the health problems Richard Simmons caused Mr. Oliveira.'

The bombshell court filing comes after months of speculation over Simmons' whereabouts. Oliveira was interviewed in a podcast that went viral, "Missing Richard Simmons," and ignited rumors that the former Slimmons studio owner was being held hostage by his housekeeper. Richard's reps shut down these rumors shortly after the release of the podcast.

Simmons was recently hospitalized for severe indigestion, which would make it the first time that he's been out in public -- to the everyone's knowledge -- in three years. However, Simmons reportedly regularly makes public outings in disguise.

The "Sweatin' To The Oldies" star posted a heartwarming Facebook post thanking his fans following his hospitalization. He ended the message with a cryptic line that hints at a return to the spotlight: "Hope to see you again soon!"