What reason does Abigail give Parris for being dismissed from the Proctors' service? What is the real reason for her dismissal?

In Act 1 of “The Crucible”, Rev. Parris’ daughter Betty becomes bewitched and there is no explanation for it.  While Parris attempts to find out what Abigail, Betty, and the other girls were doing in the forest on the previous night, he questions Abigail about why she had been fired from her previous job for the Proctors and why no one else in the village is willing to hire her.  Abigail tells Parris that she was fired because she refused to be a slave to Elizabeth Proctor.  However, later in the act we find out that the real reason for her dismissal from the Proctor’s service was that she was having an affair with John and Elizabeth found out about it and fired her.