The website claims that her own past substance abuse battle made drug use a "deal-breaker."
However, an insider from Hemsworth's camp told TMZ that the drug allegations are "bulls—t" - and that it was Cyrus' infidelity that ended their romance.
The source said of the claims: "This is another attempt by Miley to distract from her infidelity and recent outrageous public behavior."
Meanwhile, Page Six has reported that while Hemsworth wanted to settle down and live a "normal" life with his famous partner, Cyrus looked as though she was heading back to her wild ways.
They also denied that Cyrus had been unfaithful, adding: "She never hooked up with girls while she was married. It wasn’t a part of the relationship.
"There was no hooking up behind his back or with his knowledge."
Hemsworth broke his silence on the break up two days after Cyrus was pictured kissing Carter.
Posting a photo of a sunset to his Instagram page, he wrote: "Hi all. Just a quick note to say that Miley and I have recently separated and I wish her nothing but health and happiness going forward... Peace and Love."
A rep for Cyrus previously said: "Liam and Miley have agreed to separate at this time. Ever-evolving, changing as partners and individuals, they have decided this is what's best while they both focus on themselves and careers.
"They still remain dedicated parents to all of the animals they share while lovingly taking this time apart. Please respect their process and privacy."
Cyrus and Hemsworth first started dating in 2009, they had an on-off relationship with an engagement being announced in June 2012, they then split in 2014.
But in 2016, the romance was back on — as was the engagement.
On Dec. 24, 2018, it was revealed that the couple had wed in a secret ceremony at Cyrus' house in Franklin, Tenn., six years after first getting engaged.
This article originally appeared on The Sun.