Erika Girardi Filed for Divorce from Tom Because She Believes He Was 'Cheating on Her': Source

Erika Girardi allegedly believes her estranged husband Tom Girardi had multiple affairs during their 21-year marriage.

A source tells PEOPLE that Tom's alleged infidelity was the reason the Real Housewives of Beverly Hills star, 49, filed for divorce from the attorney, 81, last month. Tom has not responded to PEOPLE's multiple requests for comment.

She says "the reason she divorced Tom is because he was cheating on her with multiple women," a source close to the couple says, adding that Erika claims "she's known about his infidelity for years" but "wanted to try and save the marriage."

"When she was performing her last week on Broadway, he left her high and dry and was frolicking around town instead of supporting her and attending her shows," the insider says they were told. "She realized she would never be a priority to him and that was her breaking point."

"The split was a long time coming. The lawsuit just coincided with her decision to leave him," the source says, referencing a complaint filed in early December accusing the couple of using their divorce to embezzle money.

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According to a court complaint obtained by PEOPLE, several families who lost loved ones in a 2018 Boeing plane crash have accused the Girardis of embezzling settlement funds meant to help the families of victims on Lion Air Flight 610 and using the money to fund their "lavish Beverly Hills lifestyles."

Tom and his law firm, Girardi & Keese, are being held in civil contempt and have had their assets frozen by U.S. District Judge Thomas Durkin, who reportedly said during a hearing Monday that the "simple way to cure all of this" is to pay at least four clients that are allegedly owed $500,000.

On Tuesday, Tom's law partner Robert Keese and fellow business partners Robert Finnerty and Jill O'Callahan sued him to dissolve their venture, known as 1126 Wilshire Partnership.

According to a filing obtained by PEOPLE, Keese, Finnerty and O'Callahan claim that Tom never paid them income owed from their partnership, instead keeping the money for himself. The plaintiffs also allege that Tom took out loans against the property without their knowledge for his "own personal gain, benefit and use."

RELATED: RHOBH's Erika Girardi Did Not Sign a Prenup with Ex Tom Girardi — It 'Wouldn't Stand in His Way'

According to Erika's divorce filing, she is seeking spousal support from Tom and asking that he pay her legal fees. Meanwhile, Tom has asked to terminate the court's ability to award spousal support to Erika, and asked that she pay his legal fees.

In a statement last month, the Bravo star told PEOPLE that the divorce was "not a step taken lightly or easily."

"I have great love and respect for Tom and for our years and the lives we built together," she said. "It is my absolute wish to proceed through this process with respect and with the privacy that both Tom and I deserved. I request others give us that privacy as well."

The two first met while Erika was cocktail-waitressing at the Los Angeles restaurant Chasen's, where he was a regular, she told PEOPLE in 2018. After a yearlong friendship, he asked her out. They wed in 1999 at the establishment.

Erika was previously married to Thomas Zizzo, with whom she shares 26-year-old son Tommy Zizzo.