The 22-year-old actress, who was caught cheating on boyfriend actor Robert Pattinson by having an affair with director Rupert Sanders, is hooked to the computer.
"Kristen is hooked on Googling herself and seeing all of the horrible stuff people write as a way of punishing herself," thesun.co.uk quoted a source as saying.
"When Kristen searches results about the films or her name on Twitter she ends up focusing on all the wild, negative comments against her and it really gets her down," the source added.
However, the couple have now reunited, and Pattinson asked Stewart not to give herself pain.
"It's not healthy and Robert has said it must stop. He has told her she needs to stop torturing herself and move on," the source said.
The couple met on the sets of "Twilight" in 2008 and will soon be seen onscreen in "Breaking Dawn 2", the final movie of the franchise.