Mel Gibson’s wife has filed for divorce from the actor after 28 years of marriage.

Robyn Gibson cited irreconcilable differences in the papers, which she signed last Thursday. According to TMZ, there is no prenuptial agreement between the couple, who married in 1980.

Gibson is worth an estimated $900 million. Robyn Gibson is reportedly seeking spousal support, joint custody of their child Tom (the only minor of their 7 children together) and attorney fees.

But some sources say that those "irreconcilable differences" may include Mel vacationing with another woman.

According to RadarOnline.com, the "Braveheart" star was recently spotted at his Costa Rica vacation home with a stunning Russian musician named Oksana.

On March 4, Radar caught the two in a loving embrace on the beach. According to the report, several of his sons, their girlfriends and other guests were all on hand for the trip.

Still, according to People magazine, the couple has been separated for three years, reportedly breaking up shortly after his DUI arrest in Malibu. According to that report, the couple's separation has been quite amicable.

The film "Mad Max" brought Gibson his first international attention in 1979, closely followed by the critically acclaimed "Gallipoli" and the "Mad Max" sequel "The Road Warrior."

Gibson has since gone on to make a mix of crowd-pleasing shoot-'em-ups such as the "Lethal Weapon" franchise, and has established himself as a director. 1995's "Braveheart" earned Gibson two Oscars for best picture and best director.

He also produced and directed the surprise blockbusters "The Passion of the Christ" and "Apocalypto," which broke box-office records for foreign language films in its opening weekend in several countries.

RELATED: Click here to see the photos from RadarOnline.com.

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The Associated Press contributed to this report.