Sweet Valley High - Season 1 Episode 15 Stolen Diary

Feeling left out because Liz appears to spend all her time with Todd, Jessica tells Peggy that Todd is available in the hope of breaking them up. Peggy throws herself at Todd and Liz catches them, promptly breaking up with him. Then Jessica arranges a date between Liz and Chris. When Liz rejects Chris after one date, he uses her found diary (which she accidentally dropped) to spread her secrets around school. Pretty soon all of Liz's friends are mad at her, but Jess refuses to believe that Liz could spill their secrets, and promptly goes out to set things right.