Bestselling urban fantasy novelist Sherrilyn Kenyon has filed a lawsuit against her husband that accuses him of poisoning her for financial gain, as well as attempting to destroy her career and reputation, in what she described as a “Shakespearean plot against her”.

Kenyon, author of the chart-topping Dark-Hunter series, is suing Lawrence R Kenyon II, as well as two individuals employed by the Kenyons, for up to $20m (£15.5m).

The suit, filed in Williamson County in Tennessee, accuses Kenyon II, together with one of the two assistants, of “assault by poisoning”, as well as “intentional interference with business relationships [and] prospective contractual relations” and invasion of privacy. Kenyon also accuses both of the assistants of helping her husband to embarrass her in front of fans and isolating her from her friends and employees.

In the most explosive of the allegations, Kenyon says that she suffered from symptoms including tachycardia, severe body tremors, hair loss, memory loss, crumbling teeth, “excruciating” stomach cramps and severe anaemia, which she claims were caused “by the toxins she’d been unknowingly ingesting in her tainted food and drink”. The complaint states that Kenyon II and one of the accused assistants “would force her to eat and become enraged any time she failed to consume”.

After her husband filed for divorce, Kenyon says that she had her blood, nails and hair tested for toxins, and found that her body had high levels of lithium, tin, barium, platinum and thorium.

The lawsuit states that Kenyon felt it had become “obvious that they had systematically poisoned her since 2015 … In March 2018, the longer Mr Kenyon was away from home, the better Ms Kenyon’s health was getting.” It also lays out the emotional abuse that Kenyon claims she was subjected to for years, as well as attempts to interfere with her professional relationships. She also alleges that Kenyon II rewarded both the two accused assistants financially when they helped him, and that all three wanted to “destroy her professionally and emotionally”.

“It was unclear to [Sherrilyn Kenyon] why her husband … would orchestrate this Shakespearean plot against her when he was lavished with expensive cars and other personal services that could only be obtained through [her] career success,” it opens. “[She] now believes that it was more than the profuse insecurity and insidious jealousy of her success, but Lawrence Kenyon stood to gain millions of dollars upon her demise through life insurance and the value of her estate, including her copyrights and trademarks.”

Kenyon, whose books have sold millions of copies, first announced that she had filed the lawsuit against her husband in a newsletter to fans. “Out of the blue I was viciously and painfully struck down by a bevy of strange, inexplicable and baffling symptoms. This past spring and summer, after new rounds of testing, my doctor finally learned the cause of it all: Someone close to me was tainting my food,” she wrote. “Rest assured, I am much better today as my symptoms have dramatically improved since this past March when it all came to light and the authorities were notified … But I and the authorities are still trying to determine who all had a hand in doing this to me.”

The Tennessean newspaper, which first reported on the suit, also printed a photograph of Kenyon’s heavy metals test on Tuesday, and said that the Williamson County sheriff’s office was in the middle of an ongoing investigation into the alleged poisoning.

Kenyon II’s lawyer, Sean Aiello, confirmed to the Guardian that he had filed a motion to consolidate the new case with the Kenyons’ ongoing divorce case. The new motion claims that the “overwhelming majority” of Kenyon’s lawsuit contains “outlandish allegations”.

In a statement on behalf of Kenyon II through his lawyers, he said: “There can be no question that Sherrilyn Kenyon is a brilliant fiction writer, but it is apparent that she has irreparably blurred the line between fiction and reality. These astonishing and unsubstantiated allegations may stand as her best fantasy creation yet. When Lawrence Kenyon filed for divorce a year ago, he wanted nothing more from his wife other than an amicable divorce. He is saddened that the stress of these proceedings has brought out the worst in such a talented writer.”

The statement also confirmed that no charges had yet been brought against Kenyon II by local law enforcement.

“Mr Kenyon hopes that his wife gets the help she needs during this divorce process, and regrets that what would have otherwise been a private dissolution of a marriage has been shoved into the public arena,” the statement ends.