Earlier in Act I, Abigail and her friends were seen dancing in the woods which drew a lot of suspicion in Puritan Salem. Parris' daughter Betty has since fallen into a trance and residents seem to think her condition is a result of the dancing in the woods and withcraft. At the end of the chapter, Abigail falls under heavy interrogation for her part in the dancing and her cousin's condition. It's at this point that Abigail decides to confess all the things she did (and more) and "come back to Jesus. However, she uses the colored housekeeper Tituba, from Barbados, as the scapegoat accusing her of making Abigail interact with the devil.
Some of the "wrong" things Abigail does at this point is admit to dancing with the Devil, "writing in his book", and drinking blood. Act I ends with Abigail and the other girls calling out names of other women in town who have made deals with the devil. These names include those of her enemies and others who have a questionable reputation that people would easily believe had an affiliation with the devil.
The truth is Abigail asked Tituba to make a "charm" for her and use witchcraft to harm Goody Proctor, whose husband Abigail recently had an affair with.