SACRAMENTO, Calif.—A mother of three children who were killed by their father at a Sacramento church had sought a restraining order out of fear for their safety, court documents indicate. David Mora, 39, also fatally shot a male chaperone who was supervising a visit with his daughters Monday afternoon before taking his own life at The Church in Sacramento, a nondenominational Christian place of worship, officials said Tuesday. Mora had been living at the church, Sacramento County sheriff’s Sgt. Rod Grassmann told KXTV-TV. Mora’s estranged girlfriend had been with him for about 15 years but she sought a domestic violence restraining order against him last April, describing him in court documents as jealous and mentally unstable. “He threatened to kill me if he ever caught me cheating. … He has choked me in the past,” the filing said. Mora “said that he has not killed me because he would not …