A Westchester woman who says she was sexually assaulted by a fellow Stony Brook University student in an attack so painful she couldn’t sit, eat or sleep afterwards, is suing the Long Island school for “deliberate indifference” to her ordeal.

The accuser claims she was at an on-campus party in January 2014 when a male student switched her mixed drink with straight liquor to get her “overly intoxicated so that she would later have sex with him,” according a lawsuit the student filed against the SUNY college and her accused attacker.

The Post is withholding the names of both students.

They went to his dorm room and kissed, but when the senior social-work major wanted to stop, he “overpowered” her, she says.

She was forced to perform oral sex and blacked out, only to be reawakened by the physical pain of the continuing assault, which left her with “internal pain,” flashbacks and panic attacks, she alleges in court papers.

The victim eventually woke up and was able to leave. Two days later, at the urging of friends, she went to campus police.

Campus cops failed to properly investigate the assault, didn’t document her injuries, and discouraged her from going to law enforcement, the suit says.

“I thought I was going to get some type of justice,” she told The Post, but instead was made to feel “like I was the one who did something wrong, and not him.”

When she pushed the administration, it required her to testify in an internal disciplinary hearing during final exams in May which, she says, amounted to a kangaroo court.

She was asked to “prosecute” her alleged attacker, who was allowed to cross-examine her with a paper screen separating them, according to court papers.

The school put her “in the impossible position of being her own surrogate lawyer while finishing her college education, attending to her job responsibilities, and suffering the trauma from the original attack,” according to the Manhattan federal court lawsuit.

University officials told her she would know the results of the hearing in 24 hours. A week later, on her graduation day, they told her they had cleared the male student of wrongdoing.

Stony Brook “completely misguided, mistreated and essentially neglected” her, the 22-year-old said.

“There were months when I felt like I was a shell of a person,” she says.

The male student is now in his junior year. The victim was granted an appeal in August, which Stony Brook has ignored, she claims.

A university spokeswoman said the school “is committed to the prevention of sexual assault and violence on campus.” The male student could not be reached.