In The Crucible, what is finally admitted from the girls when the adults leave them alone?

This section of the play comes in Act One, when Parris and
Putnam leave Betty in the care of Abigail and the girls. Crucially, this is the only
time that we see the girls by themselves in the entire play without an audience. Here we
see that they are desperate to save themselves and they try to work out their story of
what they should tell the Reverend Parris about their night in the woods. Interestingly,
what we also see is Abigail and Mercy bullying and trying to dominate Mary Warren as she
rushes in, scared and worried about the potential consequences of their actions.
However, perhaps far more disturbingly, when Betty wakes up, she tells us that Abigail,
as part of a spell, drank blood as a charm to kill John Proctor's wife. At this, Abigail
slaps her hard on the face and then decides on the story that they are to
tell:

Now
look you. All of you. We danced. And Tituba conjured up Ruth Putnam's dead sisters. And
that is all. And mark this. Let either of you breathe a word, or the edge of a word,
about the other things, and I will come to you in the black of some terrible night and I
will bring a pointy reckoning that will shudder you. And you know I can do it; I saw
Indians smash my dear parents' heads on the pillow next to mine, and I have seen some
reddish work done at night, and I can make you wish you had never seen the sun go
down!

Abigail already
evidences the power and domination that she goes on to show by leading the group of
girls in their denunciations through the rest of the play. We discover that she has
willingly partaken in a charm to kill John Proctor's wife so she can marry John Proctor,
and we also see her physical, psychological and mental bullying that she employs to
great effect. The stage is set for the rest of the tragic
action.