The 33-year-old filed for divorce last week, apparently blindsiding the "Mission: Impossible" star who was not aware of his wife's intentions, reported Contactmusic.
"They met years ago through their mutual friend, Keanu Reeves, and Sandra knows all too well about being in a bad marriage - she's been a real comfort to Katie," a source said.
Bullock herself divorced two years back from husband Jesse James.
It is said that Cruise and Holmes are hoping to settle their divorce out of court, apparently calling a "temporary truce" when it comes to legal proceedings.
A source said that Cruise, "doesn't want his family dragged through the mud. They love their daughter."
However, Holmes is "dead-set" on retaining full custody of daughter Suri, with an insider saying, "Katie is not going to compromise on certain issues, all regarding Suri."
