Magdalene sisters - spoilers

Just saw this amazing and harrowing movie. One of the best I’ve seen this year. Quick question though to those who have seen it. I was a bit confused by the actions of the pretty sister Bernadette. Though most of the movie she acts to save her skin, on two different occasions, she acts curiously toward her fellow sisters. The first occasion is when she steals Crispin’s medallion and doesn’t give it back to her after she notices her smiling in a dream. The reason she gives when questioned about it by Margaret is that she wanted her to suffer. Later on when the old woman whose name I forget was dying, she taunted her, telling her to die already. She then finds the old woman dead, says she got what she deserved, and then kissed her forehead. Maybe I’m reading too much into these scenes but it seems to me that Bernadette wanted the two sisters to suffer in order to reach heaven. In the first instance she withheld the medallion when she noticed Crispin’s happiness and in the second instance she bestowed an act of kindness on the old woman after she died (and presumably suffered). So…three possibilities: (1) Bernadette is kind and wanted through bestowing suffering to help out these women; (2) Bernadette is evil and sadistic and wanted to make sure that these two women sufferred as much as she did; (3) neither of these possibilites pan out and I am reading way too much into this character. What do you think?