The model is among the multiple women to have come forward with accusations against Manson after his former partner Evan Rachel Wood alleged that he “horrifically abused me for years” in February.
Smithline later named the shock rocker as her alleged abuser in an Instagram post shared that same month.
Manson – real name Brian Warner – has denied all the allegations, calling them “horrible distortions of reality”.
*The following interview contains graphic references to sexual assault that some readers may find upsetting*
In a new interview with People, Smithline has opened up about the alleged abuse Manson inflicted on her.
Watch: Marilyn Manson's ex girlfriend describes shocking sexual abuse
She accused Manson of raping her, cutting her and locking her in a glass, soundproof room – called “the bad girls room” – whenever she “pissed him off”. She claims to have been locked in the room more than 100 times.
Smithline recalled: “He kept telling me, ‘You can’t rape someone that you’re in love with.’”
“There’s a difference between waking up to someone having sex with you nicely in the morning and waking up tied up with someone having sex with your unconscious body, being tied up and screaming and not enjoying it, and him laughing, like sadistically, or gagging my mouth or something.”
The 36-year-old went on to claim that she was “brainwashed” by the musician over the course of two years, accusing him of carving his initials into her thigh.
“He cut me on my stomach and then drank my blood. Then, he had me drink his,” she said. “The more I let him hurt me, the more I loved him and the more I was proving myself to him.”
According to the publication, Manson had first contacted Smithline to discuss an acting role in a film before his behaviour became “slowly more and more invasive”.
A spokesperson for Manson has denied Smithline’s new accusations in a statement published by NME, stating: “There are so many falsehoods with her claims that we wouldn’t know where to begin to answer them.”
It went on to refute the her claim that the pair’s relationship lasted two years between 2010 and 2012, instead alleging that it “didn’t last one week”.
Recently, actor Esmé Bianco sued Manson and his former manager Tony Ciulla. Bianco, best known for playing Ros in HBO’s Game of Thrones, alleged that the singer raped and sexually battered her.
The complaint also alleged that Manson, Ciulla and Ciulla’s management company violated human trafficking laws by bringing her from London to Los Angeles under the assumption that she would be acting in a music video that never came out and a film that was never produced.
Bianco first went public with her claims against Manson in February, describing the alleged abuse she experienced when they dated in 2011.
In the wake of the allegations from multiple women, Manson has been dropped from his record label, Loma Vista. His booking agent CAA and longtime manager Ciulla also announced it had severed ties with him.
Manson’s appearances in the TV series American Gods and the Creepshow anthology have also since been removed.
Watch: Marilyn Manson sued by ‘Game of Thrones’ star Esme Bianco over alleged sexual assault
If you or someone you know is experiencing domestic abuse, you can call the 24-hour National Domestic Abuse Helpline, run by Refuge, on 0808 2000 247, or visit their website here.