Smallville star Allison Mack says Nxivm sex cult is ‘biggest regret of her life’ ahead of her sentencing

The actor said her time in confinement has allowed her to grapple with the pain she caused other cult members

Allison Mack, one of the stars of Smallville and considered to be the second in command of the NXIVM sex-cult released a letter ahead of her sentencing hearing apologising for the pain she caused the people she pulled into the cult.

Ms Mack was a prominent and powerful member of the cult, considered by some to be the right-hand of the group's leader, Keith Raniere.

She said her devotion to Raniere was "the biggest mistake and greatest regret of my life" and apologised to "those of you that I brought into Nxivm”.

"I am sorry I ever exposed you to the nefarious and emotionally abusive schemes of a twisted man," she wrote.

Ms Mack was instrumental in convincing women to participate in a sub-group within the larger cult in which they were branded with both her and Raniere's initials and pressured into having sex with the cult leader, according to prosecutors.

She said in her letter that she has been confined to her home awaiting her sentencing.

"This period of isolation has been the most devastating, but transformative times of my life," she wrote.

She said her confinement allowed her to confront the "darkest parts of myself" and accept the pain that she caused to "people I love”.

“It is now of paramount importance to me to say, from the bottom of my heart, I am so sorry … I threw myself into the teachings of Keith Rainire [sic] with everything I had,” she wrote.

She also noted that during her time with the cult, family and friends tried to pull her out of the organisation, but said she rebuffed the efforts.

"I pushed you away and silenced myself toward you when you were trying to save my life ... I lied to you, again and again, in order to protect the delusion I was so deeply committed to believing," she wrote.

Raniere was sentenced to 120 years in prison after being found guilty of charges including alien smuggling, sex trafficking, extortion and obstruction of justice.

The cult leader has been moved to a high-security prison in Arizona that previously housed mob boss James "Whitey" Bulger, Ross Ulbricht, the founder of the "Silk Road" black market, and Larry Nassar, who sexually abused members of the US Gymnastics team.