Lily Allen said she was made to feel like a "nuisance rather than a victim" by police investigating a stalker as she revealed horrifying details of the seven-year ordeal.
The singer was pursued by a man who barged into her bedroom as she and her children slept, said he wished to stab her through the face and spent nights lurking in her garden.
However Allen said she was denied the support she expected when she raised her concerns with police.
Investigators destroyed evidence that supported her case, gave her a panic alarm for a matter of months and even refused to allow her to see and then keep a photo of her stalker, she told The Observer.
The long campaign of harassment has left her "a changed person", Allen said after she finally saw the man convicted.
She said: "It was not special attention I looked for. It was reassurance and validation. The police made me feel like a nuisance, rather than a victim."
The nightmare began in 2009 when a Twitter follower using the handle @lilyallenRIP appeared claiming to have penned one of her hits.
Behind the tweet was Alex Gray, a man in his early 20s from Perth, who then sent abusive rants, accusations and suicide threats in letters to her flat, her sister's home, her record company, and her management, that were in turn handed to police.
Then, when someone in the crowd at a gig held up a banner that read "I wrote The Fear", she called officers in again. After lending her a panic alarm for a few months they reportedly took it back.
According to Allen she was then denied the chance to see a picture of Gray. When officers eventually did they would not let her keep it.
The stalker progressed to banging on her door and spending nights in her back garden, before a terrifying incident on October 13 last year when she awoke in the early hours to find someone wrenching at her bedroom door.
She said: "This guy came steaming in and I didn't know who he was. I recoiled and he ripped the duvet off, calling me a 'f****** b****' and yelling about where his dad is."
Gray was forced from the property by a friend and disappeared. The police were called and she later found her handbag was stolen, although investigators were "uncomfortable" with her suggestion it was her stalker, she told the newspaper.
Then, when she found the handbag burned on the bonnet of her car Gray was eventually caught and charged with burglary.
However Allen said she felt she "hit a brick wall" when she tried to raise the stalking with police, who she said were keen to pursue the burglary in isolation.
"What I give a s*** about is a man who is saying he wants to put a knife through my face," she said.
"I wrote to the police and asked why they weren't using these letters going back to 2009, and then I got a short note saying they had been destroyed 'according to police protocol'. No apology, no explanation."
Gray, now 30, was eventually charged with burglary and harassment, although the stalking count reportedly did not cover anything before 2015. He was convicted at Harrow Crown Court this month and will be sentenced in May.
Allen said she wanted answers from the police: "I'm not angry at Alex Gray. He has a mental illness. The system has failed him. But until he gets the right treatment and the right help he needs, then I'm not safe.
"You can throw the book at him, put him in jail, but he'll still be coming out. And the victim is never safe."
A Metropolitan Police spokesman would not comment on Allen's case but said they take stalking and harassment "extremely seriously".