Both Sanders and Stewart issued public apologies for hurting their respective partners after photos were published July 24 showing the director and his "Snow White and the Huntsman" leading lady embracing and kissing.
Sanders and Ross have been married seven years and are the parents of two children.
Stewart has been dating Robert Pattinson, her co-star in the "Twilight" film franchise, for several years.
A source told People.com Sanders and Ross have not seen each other since Sanders confirmed he cheated on her; however, the couple have not decided whether to stay together or split up.
"She's been focused just on her kids through this," the insider said.
"It's what she cares about the most," the source said. "Now she's really feeling strong and looks forward to resuming her life."