Liberty Ross, Sanders' wife of more than nine years, filed for divorce Friday in Los Angeles citing irreconcilable differences.
Ross' filing cites irreconcilable differences for the couple's breakup. They have two children, an 8-year-old daughter and 6-year-old son.
The model-actress is seeking joint custody of the children and spousal support from her estranged husband, who directed Stewart in "Snow White and the Huntsman."
TMZ, which first reported the filing, stated that Sanders also filed divorce paperwork but it was not available on Monday.
Stewart, who has been dating "Twilight" co-star Robert Pattinson, apologized for her fling with Sanders in July after it was revealed by US Weekly.