Jason Sheats thought his wife was going to tell Taylor, 22, and Madison, 17, that their parents were getting a divorce.
Instead, she pulled out a gun and fatally shot her daughters, Fort Bend County Sheriff Troy E. Nehls said in a news conference Wednesday. Minutes later a Fulshear police officer shot the mother outside the home when she refused to put down her weapon.
Christy Sheats had "ample time and opportunity" to kill her husband "but she chose not to," Nehls said, sharing details of the incident for the first time.
"He felt Christy wanted him to suffer," Nehls said, repeating what Jason Sheats told him.
"Mr. Sheats stated Christy knew how much he loved Taylor and Madison and how much they loved him," Nehls continued.
"By killing his children Mr. Sheats will have to live the rest of his life with this horrible memory."
The daughters were found on the street with gunshot wounds. Taylor died at the scene; her younger sister Madison at a hospital.
Jason Sheats told police his wife suffered from depression, Nehls said. She was taking "numerous" prescription medications and seeing a therapist. She had been admitted to a private mental health facility three times in recent years for attempted suicide, Nehls said.
Jason Sheats told police that his wife of more than 20 years began a "downward spiral" after the 2012 death of her beloved grandfather, from whom she received the gun, Nehls said. Her mother died two months later, worsening her condition.
Days before the shootings Christy Sheats had a fight with her oldest daughter in which she tried to ground Taylor and forbid her from seeing her fiancee, Jason Sheats told police. The father disagreed with his wife that grounding was an appropriate punishment for a 22-year-old, Nehls said.
Christy Sheats shot her daughters inside the home, starting with Taylor, Nehls said. Taylor sustained a single gunshot through the back. Madison was shot through the neck.
After they were were shot Jason Sheats managed to run behind the couch and get them outside, Nehls said. Both daughters collapsed in the street.
By then, the sheriff's office had responded to a 911 call and confronted Christy Sheats outside the home. When she advanced at them with the gun, refusing commands put it down, an officer fatally shot her.
Jason Sheats did not appear at Wedndesay's news conference but gave the sheriff's office permission to share his account, Nehls said.
"We look at him as a victim," Nehls said. "This is something he is going to have to live with for the rest of his life.
"She accomplished what she set out to do, which is to make him suffer."