Kristen Stewart’s fling with her director: How long did it last?

Kristen Stewart apologized last week for a “momentary indiscretion” that was a slap in the face to beau Robert Pattinson, but according to her paramour’s brother-in-law, the actress might be stretching the definition of “momentary.”

Far from the day-long dalliance caught on camera, Stewart’s fling with director Rupert Sanders may have gone on for months, Leopold Ross told Britain’s the People publication on Saturday. Leopold, younger brother to Sanders’ wife, Liberty Ross, lives in L.A., where his sister and her husband had also relocated so he could give it a go in Hollywood.

“It was from the last half of filming and all through post-production, clear into last week,” he told the People.

[Updated, 5:45 p.m. July 30: Or did Leopold Ross say that at all? A source reportedly close to Sanders told Gossip Cop on Monday afternoon that the quotes and information attributed to Leopold Ross actually came from “an imposter or were fabricated” and that the British musician, now L.A.-based, never spoke to the tabloid site. According to People magazine (which also cited a Sanders-camp source Monday afternoon as saying the info was untrue), the editors of the People were standing by their story.]

Liberty Ross, 33, and Sanders, 41, met when she was a teenager, the website said. “Snow White and the Huntsman” was Sanders’ feature-film directing debut.

PHOTOS: KStew and RPattz through the years

Paparazzi caught Stewart, 22, and Sanders making out in and around L.A. on June 17. The photographer who first spotted Kristen with a Man-Who-Wasn’t-Rob decided to call for backup, and ultimately three more shooters were also tailing the apparently oblivious couple.

“He seemed more cautious,” a witness to their outdoor embrace told Us Weekly. “She was lost in the moment. It was clearly all she was thinking about.”

The owner of the photo agency involved told The Times he’d decided against shopping the pics around town in an effort to keep the story under wraps, choosing instead to go only to Us Weekly. The news broke online last Tuesday when fans spotted a thumbnail version of the mag’s cover online. The apologies followed Wednesday via People magazine.

TIMELINE: Kristen Stewart cheating scandal

“There was no question when we saw those pictures that this was going to be one of the biggest stories of the year — if not the biggest,” Scott Cosman, owner of FameFlyNet Pictures, told The Times.

“And I’m not sure the ‘Twilight’ fans would have believed the news without the undeniable photographic evidence.”

More photographic evidence emerged over the weekend: A U-Haul set up Saturday outside the house Robsten have been sharing in Los Feliz. According to People, Pattinson, 26, asked Stewart to pack her things and go — that after he reportedly bugged out for a while himself.

So, was the “indiscretion” a one-time deal? Or do you agree with the Ross family’s suspicions of a months-long affair, with Stewart apologizing only for the “moment” when they got caught? Those who believe Robsten was all just staged for the “Twilight” publicity, feel free to weigh in as well.

RELATED:

Kristen Stewart apologizes for ‘indiscretion’ with married director

Rupert Sanders apologizes for Kristen Stewart hookup; fans react

Robert Pattinson and Kristen Stewart make Comic-Con 2012 a family affair

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