Kim Zolciak and Kroy Biermann's split 'may be a nasty divorce,' says legal expert: Here's why

Bravo fans were shocked on Monday by news that Kim Zolciak filed for divorce from Kroy Biermann. Viewers watched their love story unfold on television for nearly a decade, but it sounds like we need Andy Cohen and a camera because one legal expert expects this to turn ugly.

TMZ obtained Biermann's divorce filing and he's seeking sole legal and physical custody of his and Zolciak's four children. The former Real Housewives of Atlanta star asked for primary physical custody and joint legal custody in her petition. Celebrity divorce lawyer Charlotte Christian tells Yahoo that Biermann is sending a message with the document.

"The request for sole custody indicates that this may be a nasty divorce as most divorce complaints ask for joint custody to some degree," Christian explains. The Tardy for the Party stars are parents to Kroy "KJ" Jagger Jr., 11, Kash, 10, and 9-year-old twins, Kane and Kaia.

"To be awarded sole custody, one parent must prove that the child's best interest would be served by being with one parent a majority of the time, with that parent making the parenting decisions and the other parent only visiting the child," Christian continues. "Generally speaking, for a sole custody award, one parent must be unwilling or unable to parent and sole custody is rarely granted."

Zolciak is mother to two daughters from prior relationships, influencers Brielle Biermann, 26, and Ariana Biermann, 21. The former Atlanta Falcons player legally adopted them years ago, but they are not impacted by custody issues, given their ages.

The divorce news came on the heels of a TMZ report that Zolciak and Biermann are in financial trouble. They apparently owe $1.1 million in unpaid taxes and their Georgia mansion went into foreclosure earlier this year. In his filing, the ex-NFL star requested Zolciak maintain all financial documents.

"If the tax bill is in both of their names, they will both be liable for the taxes," Christian explains. "The IRS trumps divorce decrees or any agreements between the parties. The IRS will come after both of them separately for the tax debt that will be shouldered by both of them."

A rep for Zolciak had no comment on the situation when reached by Yahoo. Neither she nor Biermann has spoken publicly about the divorce — but he appears to have subtly addressed it on Instagram.

Biermann's Instagram bio reads, "Husband. Father to six perfect munchkins. Athlete. You can Google Me & see I wasn't Tardy for that Party."

Cohen, who knows the former couple well, said he was "very surprised" by the news.

"I was very surprised. That was not the news I ever expected to get. They seemed so much in love and just together. I mean, they were a couple that, yeah, I thought they were in it for the long haul," the executive producer shared on on Tuesday's SiriusXM's Andy Cohen Live. "Sorry to hear that there may be some financial issues. TMZ is reporting that they owe a million dollars to the IRS. Texted a little bit with Kim yesterday, sent my condolences because it's a sad thing. They have kids and that was just a couple that seemed very much in love."