The 51-year-old model and the Marseille footballer began dating in 2017 after meeting at the Monaco Grand Prix.
On Tuesday, Anderson took to Instagram to confirm her split from Rami.
“It's hard to accept,” the Baywatch star captioned a black and white photograph of her and Rami.
"The last (more than) two years of my life have been a big lie."
The actor continued, writing that she was “devastated” following the split. Anderson also described her ex-boyfriend as a “monster” and suggested the French sportsman cheated on her with another woman.
“He lied to all. How is it possible to control 2 women’s hearts and minds like this [sic]” she added.
Rami has not yet responded to the claims.
Anderson concluded her post, tagging the National DV Hotline – a domestic violence charity which she has donated money to on numerous occasions in recent years.
“How could I have helped so many people @ndvhofficial and not be wise enough or able to help myself,” she wrote.
Several of the star’s fans have sent their messages of support in the wake of the break-up.
“Pamela keep strong, beautiful lady,” wrote one user.
“I’m so sorry,” added another. “Narcissists will always take advantage of empaths. You are a beautiful, intelligent and inspiring woman, you deserve better.”
A third added: “I can't believe that a woman like you gets hurt over and over again.
“You deserve all the best and love in the world and I hope someday you'll find it! We love you.”
Anderson recently moved to France to live with Rami and previously described him as “fantastic”.
“I love him, of course. You have to be very brave and enjoy things,” the model told The Sun.
“I care about him a lot and we get along. Who knows how long this world is going to last with the way it is going. You might as well enjoy your life.”
Anderson was previously married to Motley Crue drummer Tommy Lee, with whom she shares two sons, Brandon and Dylan.
She later married musician Kid Rock and American poker player Rick Salomon.
The Independent has contacted Adil Rami’s representatives for comment.