Lily Allen says she was made to feel like a "nuisance rather than a victim" by UK police investigating a stalker, as she revealed horrifying details of the seven-year ordeal.
The British singer was pursued by a man who barged into her bedroom as she and her children slept.
She 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 newspaper.
The long campaign of harassment has left her "a changed person", Allen said after she finally saw the man convicted.
"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," she said.
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 Scotland, 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 let her see it, 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.
"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."
Speaking to The Observer, she said: "I had all sorts of metal shutters and locks on the doors but I'd been cooking and burned a pan and opened the back door. I closed it but forgot to lock it when I went to bed. [Later than night] I sat up in bed and looked and the door handle was twisting round.
"For me, it was too much of a coincidence that the only night I had left the shutters up, this man came in. I believe he had been spending a lot of time out there in my garden, watching."
Lily believes her stalker had a knife when he broke in and has slammed the police for not taking her claims of stalking seriously.
She said: "This was something that started in 2009 with a tweet and ended in 2015 with him in my house and, I believe, with a weapon.
"I'm lucky in that I had the money and the motivation to take action myself. I want answers from the police. If they treat me like this, how the hell are they going to treat everyone else?"
Gray was forced from the property by a friend and disappeared. The police were called and Allen 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.
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."
The mother of two also admitted that the ordeal has changed her completely.
She said: "It has affected how I live my life. I'm very wary, I have trust issues. It impacts on your relationships, everything. I'm practically a hermit now! I'm very aware of trying not to overdramatise what's happened, I'm aware that some fears are irrational; I know he is in prison. If I hear a bang, every little noise makes me start. I see his face in people in the street. I've had to leave the flat I loved, move nearer a main road with lots of CCTV about."
A Metropolitan Police spokesman would not comment on Allen's case but said they take stalking and harassment "extremely seriously".
- PAA, Bang! Showbiz