A 17-year-old boy who raped a 47-year-old woman at knifepoint during a burglary in her College-area home was sentenced Friday to 25 years to life in state prison.Chadrick Robertson, who pleaded guilty Feb. 19 to felony rape, was a "career criminal" by the time he committed the sexual assault, with convictions for graffiti vandalism, theft and burglary, said Deputy District Attorney Patrick Espinoza.Five days before the rape, Robertson was released from Juvenile Hall and placed with his mother, Espinoza told Judge Jeffrey Fraser.Around 4 a.m. last Aug. 13, Robertson climbed through an unlocked window of a home on 67th Street near El Cajon Boulevard, apparently planning to commit a burglary, according to San Diego police.Armed with a knife, he demanded money from the woman, and when she said she had none, he raped her, police said.During the sexual assault, she cut him with a drinking glass, and he hit her with a glass, causing her to bleed so badly that she begged him to let her go to a hospital, which he finally did.DNA evidence found on a cigarette at the scene matched a sample taken from Robertson when he was convicted of robbery in 2007, the prosecutor said.The victim -- who was present in court -- wrote a letter to the court, which was read by Espinoza.She said the horrors of what happened will haunt her forever."During the attack, I was choked until I passed out," she wrote."Just before it went dark, I was sure I would die and I thought, `I hope they find the knife and get his fingerprints. This is where my body will be found."'She said she now sleeps with the lights on, can't take out the trash and won't see friends unless they come to her home."Most of the time, I make excuses to avoid seeing anyone because the pity in their eyes is more than I can bear," she wrote.She bemoaned the fact that Robertson, at 17, was unrepentant and a habitual criminal."When I begged him to leave, he threatened my life," she wrote. "When I began to pray, he punched me in the face and told me to shut up. When I screamed for help, he choked me unconscious. He tortured and threatened me for 1 1/2 hours without regard for the pain caused by his brutality."I believe there is a special place in hell where he will go one day. I hope he is kept in custody until that day arrives."The judge lambasted Robertson for the "vicious, callous and cruel" attack and called him the "worst of the worst.""You, Mr. Robertson, are as bad as they come," the judge said. "This was every woman's worst nightmare."Fraser, citing Robertson's juvenile record, said "at a very young age, he showed he was a predator. The juvenile justice system failed us here."He told the woman that Robertson will never get out of prison."Rest assured, he will never come back to harm you," the judge told the woman.