Dotcom took to Twitter to voice his outrage, saying: "Frustrated US DOJ prosecutors attack my estranged wife Mona, her assets & the future of our children. You know you're winning when they start attacking the people you love."
The latest turn in the long-running cases follows Mrs Dotcom's attempt to register a claim on half of her husband's restrained fortune. The US Department of Justice claims Dotcom's wealth stemmed from crime and should be surrendered.
The case runs alongside the FBI's prosecution of Dotcom on charges of criminal copyright conspiracy over which the tycoon faces extradition to the US.
The new court records include documents from the Guam divorce court, showing Dotcom and Ms Vargas were married in August 2007 and had a child that year. The couple separated in September 2008 and were divorced in May 2009, with Dotcom paying a $130,000 settlement. Two months later, the records show he married Mona Verga, as she was then, who had given birth earlier that year to his second child.
The importance of the date to the US prosecutors was a sworn statement by Mrs Dotcom that she was entitled to half his property "as I began a de facto relationship with Kim Dotcom in November 2007".
The statement was contrasted with dates from divorce court records, along with New Zealand testimony and media coverage in which Mrs Dotcom said she "met Kim" in November 2007.
The DoJ told the US district court in Eastern Virginia "Mona Dotcom cannot use the date" she met her husband to claim a de facto marriage when Dotcom was already married.
It also says Mrs Dotcom's claim on her husband's fortune should extend to his collection of exotic and luxury cars because she can't drive.
It says the cars should have also clued Mrs Dotcom in on her husband's allegedly illegal business model because of the numberplates "Guilty", "Mafia", "Evil" and "Hacker".
"Her husband's lack of discretion should have put Mona Dotcom on notice to inquire as to the sudden source of her husband's wealth."
It also argued Mrs Dotcom had already received more than the $23m she had so far claimed with Dotcom publicly announcing he had signed over the family trust to her control. The court papers estimated the trust contained shares in the cloud storage Mega service worth $35m.
The US authorities also sought and received support from NZ government lawyers to fight off Mrs Dotcom's claim. Dr Mathew Downs, senior Crown counsel at the Crown Law Office, told the US court Mrs Dotcom's claim would likely fail in New Zealand courts. He said "courts have consistently refused to allow an offender's spouse to retain the benefits of criminal offending even if she is entirely innocent".
Kim Dotcom financial facts
How much money does Dotcom have?
A lot - but he can't get his hands on any of it. There's about $10 million in New Zealand in cars and cash which is frozen by court orders. He's going back to court next week to try to access that. There is about $50 million in Hong Kong, also frozen but facing a fresh hearing. The Dotcom family trust contains $35 million in Mega shares, according to the US, but control has been signed over to Mona Dotcom.
Hasn't the money already been seized?
The money has been frozen - seizure is the next step. The US is attempting to suck the cash out of the jurisdictions where it is being held on the basis of it being ill-gotten gains.
When is the extradition hearing?
June, after yet another delay. Then there will likely be appeals (from either side) to the High Court, Court of Appeal, Supreme Court and then the Minister of Justice signs off on the extradition order. The minister's decision could be judicially reviewed - again with appeals to follow.
