Disgraced Southern Charm alum Thomas Ravenel claims Kathryn's mental illness prevents her from being a good mother.

This custody battle is downright nasty.

Now, Kathryn is firing back, and saying that Thomas has a love for drugs and a psychiatric diagnosis of his own. ...

Nobody is pulling their punches in this vicious, vicious custody battle.

According to documents obtained by The Blast, Kathryn Dennis has filed documents of her own in retaliation for Thomas' accusations.

In legal papers, Kathryn insists that Thomas "identify every prescription drug and/or illegal drug that you have used during the past 6 years."

"For each prescription drug," the papers request. "Please identify the doctor who prescribed the drug."

And she also demands to know "where you purchased your prescription drugs."

After all, plenty of people find illegal ways to obtain drugs that are perfectly legal.

In 2016, Kathryn lost custody of her children after testing positive for marijuana, which is still criminalized in South Carolina.

She regained partial custody of Kensie and Saint in early 2018. She and Thomas currently share a 50/50 split.

She wants full custody.

Now, in court documents, Kathryn alleges that Thomas threw a party in which illegal drugs were present.

"What date was it when you threw a party in your home downtown with illegal drugs present," Kathryn asks.

"And," the papers detail. "You informed fellow party participants while standing in the bathroom that mushrooms don’t show up on drug screens?"

Her implication with that question is that she probably has witnesses.

Kathryn's incident with marijuana was three years ago, but she's not the only one whose personal history includes drugs.

Thomas Ravenel once completed a 30-day rehab program.

More significantly, he served 10 months in federal prison -- which also killed his political career.

This was after his June 2007 indictment ona charge of conspiracy to possess with intent to distribute.

The drug in question was some volume of cocaine that was less than 500 grams.

Kathryn asks Thomas to produce “any and all evidence (whether photos, statements, videos, documents, etc.)” that she ”‘abuses prescription drugs.’"

As we have previously reported, Thomas accused Kathryn of actively abusing illegal substances.

He even claims that she makes a habit of buying, selling, and trading prescription medications.

Thomas' allegations say that Kathryn does this with friends, her Southern Charm castmates, and even producers on the show.

Most seriously, he claims that Kathryn has been under the heavy influence of drugs while being the sole caregiver of her young children.

Thomas has also alleged that there are vague "problems" with their children and that Kathryn is to blame.

He says that Kathryn abused substances while pregnant, causing problems for Saint, and didn't properly bond with Kensie, giving her behavior issues.

"His eustachian tubes weren’t draining, so he had his adenoids out and needed tubes in his ears," a source explained to People.

The insider characterized that this was "like lots of little kids his age who have that same problem."

Kathryn wants to see "any evaluations of your son that have been performed by a medical doctor as to his abilities."

Finally, Kathryn turns the tables on Thomas, who accuses her of a litany of psychiatric disorders.

"Have you ever been evaluated for a potential diagnosis of bipolar disorder or any other mental health issue, diagnosis or illness?" she asks.

Kathryn demands "copies of all your medical, psychological, counseling or other related records” from January 1, 2008 to the present day.

She also wants “a comprehensive print-out of all prescription drug purchases made by you” from January 1, 2014 to to the present day.

Kathryn requests “all medical and/or counseling records that you have obtained that relate to" her and the accusations he made against her.

She also wants “all rehabilitation records that you have obtained related to” her.

She demands “all drug/alcohol test results/reports that you have in your possession that you have had Kathryn Dennis take and/or which you have taken."

In other words, does he have evidence to back up his accusations?

Kathryn then suggests that Thomas has been making use of a private detective.

She wants "copies of any private detective reports, notes, emails, correspondence, videos, pictures, GPS logs, billing statements."

These should be logs "showing the time & date of surveillance and billing rate," court documents say.

"And/or any related documents obtained by your private detective," Kathryn asks. "Which have been retained by you or your counsel."

Private detectives are not attorneys, doctors, or religious figures. Their records can be subpoenaed.

Finally, Kathryn gets to the most serious and downright scary accusations against Thomas. She's not the one making these.

Kathryn asks that Thomas "identify each and every woman who has accused you of either assaulting her and/or sexually assaulting her."

Thomas is instructed to “produce all text messages, email messages and/or other communications that you have sent to or received” from a number of women.

Kathryn identifies the women in the documents, and wants record of their conversations “since January 1, 2016."

She wants "a copy of your complete file and any related documents regarding the sexual assault allegations made by" Nanny Dawn.

Kathryn also demands records of "any other women who have made allegations of inappropriate conduct by you.”

She asks for copies of “any and all settlement agreements that you reached and payments that you have made."

We have already heard of one woman whom Thomas allegedly paid to keep quiet. Kathryn wants to know how many more there are.

Finally, Kathryn wants to know if Thomas has "had any discussions" with or "about marriage and/or plans to marry Ashley Jacobs."

That's a hell of a question.

Obviously, some of this is typical custody warfare.

Allegations and insinuations about drugs and mental illness are largely unfair on both sides.

The stuff about sexual assault, however, is absolutely chilling.