Elizabeth was taken away after a warrant was issued for her arrest. A poppet was in their home with a needle stuck in it, and Abigail had suffered a similar "attack" at dinner that night.After Elizabeth is gone, Proctor roars at Mary that she will go to the court and tell them that she made the doll and put the pin in it because Abigail told her to.
Mary Warren is devastated and keeps denying that it is something she can do. She tries to scare Proctor off by telling him that Abigail will charge him with lechery if he pushes this, but Proctor is undeterred.
Mary insists that she cannot bear to go into court because she is afraid of the repercussions. She is worried what will happen to her if she testifies against Abigail, "I cannot, they will turn on me"(II, iv). Abigail has tremendous power over the girls at this point and Mary Warren knows it is dangerous to cross her.Mary Warren cannot stop her repeated protestations of "I cannot do it, I cannot!" (II, iv) as the act ends.
Mary also knows that what she and the girls are doing is wrong. Although some of the girls most likely have convinced themselves that witchcraft really is in the town among them, most of them realize that they are lying and are scared to tell the truth since they are afraid of Abigail.
Mary didn't care what happened to others in the town, but when it became very close to home with Elizabeth Proctor being taken as a witch, she wrestles with her moral compass. Mary knows Elizabeth to be a good woman since she lives and works in the home with Elizabeth. She also knows Abigail is in love with Elizabeth Proctor's husband and would do anything to get him for herself.
Mary's emotional dilemma comes from the decision to go along with her friends who are all pretending to be bewitched or to tell the truth and save her soul from eternal damnation which would cause her to be without friends in the town. This is indeed a "between a rock and a hard place" situation for any teenager.