The footage was included in a wrongful death lawsuit filed against the estate of Matthew Mitchell by the parents of his wife, Thy. She is referred to as Thy Mai in the lawsuit.
"I'm in such a deep hole," Mitchell can be heard saying at his River Oaks home on May 3.
The next day, police say Mitchell shot Mai, 8-year-old Maya and 4-year-old Maxwell before turning the gun on himself.
Their bodies were discovered inside the home on Kingston Street when the couple's babysitter told police the children hadn't shown up to school.
RELATED: Owners of Traveler's Table and their 2 children killed in River Oaks murder-suicide
According to the lawsuit, the murders were "planned and calculated."
"Gotta kill everybody," Mitchell is heard telling himself in a video clip recorded on April 27.
The lawsuit claims he was facing financial ruin and wanted to "avoid public shame stemming from financial failure and fraud he had committed."
"I blew it. I blew it for everybody," Mitchell says at one point.
"Wanted to spare her pain, spare my kids the pain," he says in another clip.
Mai's parents filed the lawsuit on July 13, asking a judge to freeze Matthew Mitchell's family's $6.5 million estate.
The suit accuses Mitchell of working with his mother and sister to move $1.4 million from family trusts to his mother's account.
After the murders, the suit alleges Mitchell's mother transferred the money back to "conceal her ... attempts to hide and protect the money." These allegations have not been proven.
Eyewitness News reached out to Mitchell's mother and sister for comment, but neither responded.
An attorney for the sister told the Houston Chronicle neither one of them had anything to do with this.
SEE ALSO: Traveler's Table issues statement after owners, 2 kids, found dead in River Oaks murder-suicide