what does the conversation in act 1 between the girls reveal about their relationship

Here is a great quote of how threatening Abigail can be to the girls,

"Now look you. All of you. We danced. And Tituba conjuredRuth 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 willbring a pointy reckoning that will shudder you. And you know I cando it; I saw Indians smash my dear parents' heads on the pillow nextto mine, and I have seen some reddish work done at night, and I canmake you wish you had never seen the sun go down!She goes toBetty and roughly sits her up.Now, you—sit up and stop this!"

Miller organizes this conversation between the girls in a rather mysterious manner. Betty accuses Abigail of drinking blood, to which Abigail reacts by telling her to shut up. Abigail feels threatened by the other girls, and she reveals this frustration by offering a threat of her own. The whole scene is rather dark and unnerving for all the characters--even for the more maternal Marry Warren.