Does sheila accept her responsibility and show remorse for her actions? What are her concerns?

Yes, Sheila takes responsibility for her own actions in her treatment of Eva. In fact, Sheila is Sheila is probably the most compassionate and conscientious character in the story. Yes, she's rather quiet, but her reserve doesn't reflect her feeling. Those feeling come out at certain moments when they can't be controlled.

The shock she feels upon hearing of Eva's death is genuine, especially as we know she didn't even know the girl. Her response to the news is, "Oh - how horrible," and her reaction to the photograph is filled with emotion. Eva had done nothing more to Sheila than laugh at a hat she's tried on in the shop, and Sheila had gotten her fired. Her complicity in the affair knocks her to the core, as she hadn't realize what her actions would cause. The following quotes may be helpful;

'And so you used the power you had, as a daughter of a good customer and also of a man well-known in the town, to punish the girl just because she made you feel like that?' (24)

In regards to her father's actions;

'but these girls aren't cheap labour - they're people' (19)