Kristen Stewart reportedly "couldn't stomach any food" prior to her Toronto Film Festival appearance.

The actress made her first public outing since news broke about her affair with married director Rupert Sanders, choosing to attend the premiere of her movie On the Road last week.

The 22-year-old was composed and calm at the event. Sources say that in reality, Kristen was feeling physically sick with nerves at the prospect of facing the public.

"She couldn't stomach any food at all on the day," a source told British magazine Grazia. "She was terrified that there would be booing and shouting."

The Twilight star was reportedly filled with paranoia that she would be greeted by jeers from the crowd thanks to her rumoured split from Robert Pattinson. In reality, many of her fans turned out to show their support.