"Twilight" star Kristen Stewart issued a statement last week calling her affair with Rupert Sanders a "momentary indiscretion" but according to the brother of the married director's wife, Liberty Ross, the two have been seeing each other since the filming of "Snow White and the Huntsman."

Sanders' brother-in-law Leopold Ross claims the affair began during production.

"It was from the last half of filming and all through post-production, clear into last week," Leopold Ross told UK's The People exclusively.

He also revealed that his sister Liberty is deeply hurt because she moved from England to Hollywood to support Sanders' career in film.

"She made some sacrifices for something she thought was worth it, now she knows, right?" he added.

Stewart publicly confessed to cheating with Sanders after intimate photos surfaced on the web of the pair together. The day after, she released a public apology for cheating on Robert Pattinson, her boyfriend of three years.

"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected," the "Twilight" actress said in a statement.

"This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob. I love him, I love him, I'm so sorry."

According to gossipcop, Stewart never had sex with the director. Sources revealed exclusively that Stewart only kissed Sanders, it was just "a mistake" and that she "feels awful." 

US Weekly reported that Pattinson is said to be "heartbroken and angry" by the affair. He was several weeks away from proposing to Stewart.

Pattinson moved out of the home they shared in Los Angeles two days later. Photos of a U-Haul truck in front of the house were taken on Saturday, according to TMZ.

Tags: Kristen Stewart Robert Pattinson rupert sanders snow white and the huntman liberty ross