In the letter to Teenage magazine's agony aunt, the writer, apparently a teenage girl, said she was raped by a friend and had "no-one to turn to".
The Dear Kelly columnist said in reply that she had "acted like a girl who had been around" and should be "grateful he wore a condom".
It also added that she was too "naive".
The teenage girl recounted a series of events in which she had lied to her parents to stay over at a boy's place unsupervised.
She drank wine for the first time and had kissed and cuddled the boy before he started to undress her. She said she had had too much to drink and did not protest.
She adds that she was unable to remember anything after, but found herself naked in bed the next morning beside him when he told her that he "didn't know" she was a virgin.
Kelly Chopard, the writer behind the column, said the victim had "acted like a girl who has been around".
"You gave the idea that everything was okay, you accepted wine, then there was the dancing, kissing," she said in her column. "You can't blame him for thinking a sexual connection was all right. Frankly, I understand why the guy misunderstood."
It added that the girl was "naive and inexperienced", adding that she could "be grateful that he wore a condom so there is little fear of an unplanned pregnancy or STD".
Ms Chopard is known for her "tough love and no-nonsense advice", according to Teenage magazine.
'Backward, sexist, victim-blaming nonsense'
While it is not known whether the letter, published last week, was genuine - nor whether the alleged rape was reported to police - the magazine's response was widely condemned.
"Can't believe this backward, sexist and victim-blaming nonsense got published," said one user on Facebook.
"This is the reason why girls are afraid to report rape. This is the reason why men feel like they can get away with it," said another user.
"How dare you, as a writer who is supposed to provide guidance, send this kind of message?"
"To think I used to love this magazine," read another comment on Facebook. "This is disgusting."
The magazine, Singapore's oldest youth publication, later responded with an official statement on Facebook, apologising and saying they did not mean to "lead to the impression that rape is acceptable".
Ms Chopard also responded with her own apology, put out by the magazine. She apologised, but denied blaming the victim.
"There is no intention of victim-blaming, just an attempt to point out that one's actions have consequences," Ms Chopard said in her statement.
"No-one can be more sorry for this girl than I."
Aware, Singapore's only specialist service for victims of sexual assault, called the column the "kind of judgmental, misinformed attitudes that many victims fear encountering".
"You don't have to use the precise words 'It's your fault' to blame a victim," Jolene Tan, head of advocacy and research at Aware told the BBC.
"She communicates blame by focusing relentlessly on the victim's alleged poor choices, remarking judgementally, and giving no indication she recognises the victim has been ill treated."
Teenage Magazine did not respond to a BBC request for comment.