The 'Missing' actress then alleges she "woke up in his bed one morning" with no recollection of how she got there, and claims she is "certain" the director drugged her before sexually assaulting her.
And Mhairi says the alleged incident left her feeling "ashamed", as she blamed herself for being "gullible".
She added: "I woke up in his bed one morning, naked, lying next to him, naked. I don't know how I got there. I don't remember anything.
"I was certain that he drugged and sexually assaulted me. I felt so ashamed. How could I have been so short-sighted, so gullible?
"I was in so much pain that I had to take painkillers for three days just to be able to stand up straight."
Following the alleged assault, Mhairi confided in her close friend and musician Sadie Jemmett, who has written a song called 'Don't Silence Me', which is based on the #MeToo movement and women who have come forward with their stories of alleged sexual misconduct.
Mhairi appears in the music video alongside over 40 other women, and she says she wants the project to be "educational" in helping to "eradicate discrimination."
She said: "I want the film to be an educational tool to bring about conversation and change with both boys and girls. My hope is that we can eradicate discrimination from a young age. Phrases such as 'boys will be boys' to excuse bad behaviour need to be expunged.
"This film honours and empowers the survivor. Often when you come forward, it becomes about the perpetrator and the survivor is lost and left behind.
"This video is for us, for the survivors. I wanted to honour survivors who have come forward before me. If the Bill Cosby story hadn't been told, which led to the Harvey Weinstein story then perhaps I would never have looked at my own story, which had been buried for years.
"By looking at what happened to me, I have been able to heal and move forward."
