I read that Dickens was very sentimental and was probably crying the whole time he wrote that scene. He was so worried about poor Oliver Twist he couldn't send him into peril one more time so he put some random kid in the burning building at the end. It doesn't work as well.

I agree with Meg about Lady D being in an emotional and societal pickle. In that society, having had a child out of wedlock was pretty much the end of your life. Her awful sister embodied the attitude that most people at the time had to a greater or lesser degree. Anyone can make a mistake is not what they would say. And if she hangs around with Esther suddenly people might put two and two together after Tulkinghorn told the story to an entire room full of people. Plus she's spent her whole life since then rigidly maintaining control of her emotions and behavior so that her secret would never get out. It's still pretty recent news to her she has a living daughter. I think, given time, she might figure out a way -- she might have that talk with her husband, or she might just say screw this and leave. She probably lost (or thought she lost) everything she'd ever wanted when her child died and whatever went wrong with the Captain went wrong. Since then nothing has mattered, I think it's difficult to readjust to something mattering.

Hope you feel better soon!