how do you think katniss feels when she hears peeta planning with the careers

Katniss would have felt let down and betrayed. She felt Peeta was different. She recalled when, as a starving little girl, Peeta gave her bread. She wanted to believe he was on her side. 

Well . . . Katniss feels uncomfortable seeing one of her fellow Tributes working with the Careers. She feels optimistic about the whole thing.