BRENTWOOD, N.H. -- A New Hampshire man was sentenced to 15 to 30 years in prison Friday for beating his wife to death with a flashlight after he came home to find she had strangled their 4-year-old son with a ribbon and tried to kill their 7-year-old daughter. Christopher Smeltzer, 38, pleaded guilty to killing Mara Pappalardo, who was hospitalized several times for mental illness. Prosecutors say she was paranoid, obsessed with death and convinced her husband and mother-in-law were plotting to take her children away. "When I walked into the room, as soon as I saw my son, I knew something was very wrong," Smeltzer told the court before he was sentenced, his voice breaking at times. "I knew he was dead. And I lost all control. Enraged, I struck my wife. I did something that was not going to bring my son back." Smeltzer was charged with second-degree murder in the November 2010 killing at their Auburn home. Prosecutors later downgraded that to manslaughter, saying he was provoked by the sight of the still bodies of their son, Mason, and daughter, Mercey. He arrived home Nov. 7 to find Mason with a ribbon around his neck and Mercey with a scarf around hers. He thought both were dead. Pappalardo tied a blue rope around her own neck in an attempt to kill herself, although prosecutors said she died from both strangulation and Smeltzer hitting her in the head with the flashlight. Smeltzer did not call 911. Instead, he snipped the ribbon off Mason's neck and removed the scarf from Mercey's. Then he took all the pills he could find -- painkillers, sleeping aids and methadone -- and lay down on the couch to die. He was awakened the next morning by Mercey, who asked if her mother and brother were breathing and requested a cup of tea. He made her one, then called his father and 911. Smeltzer, who was wearing handcuffs Friday, wept while talking about how much he misses his son. "I miss my wife as well," he said. "I miss Mara's smile and heart and the way she played with our children." He apologized to her family. "I brought more pain and sorrow," he said, adding he wishes every day he had a rewind button. Judge Tina Nadeau said if Smeltzer earns a college degree and completes anger management behind bars, his minimum sentence would be reduced to 10 years. Before Smeltzer spoke, a court-appointed guardian representing Mercey played a recording of the child reading a letter to the judge in which she said her father killed her mother and Mason. "If he loves me, why would he try to kill me?" she said. "If my daddy gets out, how will I keep safe? Please keep him in jail for the rest of his life." After that, prosecutor Jane Young got up and said the recording is contrary to statements Mercey has made in the past, in counseling and interviews. She repeatedly had said her father had taken the scarf off of her neck. She has said she remembers her mother carrying her into the bedroom, but doesn't remember what happened next, Young said. Prosecutors said there is no evidence that Smeltzer killed Mason.