Kristen Stewart to Come Out of Hiding in September at Toronto International Film Festival

Actress Kristen Stewart arrives at the 2012 MTV Movie Awards held at Gibson Amphitheatre on June 3, 2012 in Universal City, California.  Jason Merritt/Getty Images

One month after a heartbroken Robert Pattinson broke his silence during his Cosmopolis press tour, his estranged love, Kristen Stewart, will have to get back to work, too.

The Twilight actress — who has been lying low at her parents' place in L.A. since Us Weekly published photos of her cheating on Pattinson July 24 — will attend the Toronto International Film Festival in September to promote On The Road, Us has confirmed.

In the buzzed-about adaptation of Jack Kerouac's novel (which also stars Viggo Mortensen, Garrett Hedlund, Amy Adams and Kirsten Dunst), Stewart plays 16-year-old Marylou, the wife of Dean Moriarty.

In the meantime, Stewart is doing her best to prove just how sorry she is for having been unfaithful to Pattinson, whom she began dating in 2009.

The notoriously private actress released a statement July 25, begging fans — and Pattinson, above all — for forgiveness.

"I'm deeply sorry for the hurt and embarrassment I've caused to those close to me and everyone this has affected. This momentary indiscretion has jeopardized the most important thing in my life, the person I love and respect the most, Rob," Stewart said. "I love him, I love him, I'm so sorry."

A source tells Us the brunette beauty is desperate to mend things with Pattinson.

"She wants to fix things and undo the mistakes she's made," the insider says. "She's having a very hard time."

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