You might like a small book called, "When I was a Slave" by Dover Publishing. It is compiled of interviews done in 1936-1938 of ex-slaves. It was part of the WPA program to record narratives before that generation of ex-slaves died. Each chapter gives the name of the slave, their age (all mostly around 88), and where they are interviewed. In talking about their experiences, they give great insight into the mistress. One that I finished reading last night said that his mistress was the best mistress in the whole world. She brought 40 slaves to the marriage. Her husband had the land but no slaves until she married him. Because they were HER property, one of the few things that legally was recognized for a woman to own as part of her inheritance, separate from her husband - who owned everything, including her, she controlled what happened to them. In this particular interview, she never allowed her slaves to be punished or sold.
Other stories in the book are simply heartbreaking and disturbing and you can see in the narrative that the older slaves still suffered from PTSD.
Other slaves who went through heartbreaking things, were, like some people in every strata of social group, resilient, and came out the other end with a family. As one said, "their were Devils and God-fearing people walking the same road and you couldn't tell which was which by just looking."
If the mistress was good and kind and had her head together, when the Yankees came and told the slaves they were free, generally the house slaves stayed for a year or two till they figured out what to do. The field hands almost always took off. Then the house slave (or ex slave) and the mistress oftened joined forces to sell eggs, etc, to do what was needed to do to survive.
I certainly believe the morphine stuff, but I haven't read about it yet.
Their is another book by Coke Roberts called "Civil War Wives." It is about elite, white southern women. It is amazing insight into what an elite southern woman went through. She focuses on Varina Davis. And while she didn't write that she was married to the biggest nincompoop, she certainly felt it at times. Later in her life, she became a great friend of Julia Dent, which caused shock and awe among southern friends. But, Varina was often (along with other plantation wives I've read about), left alone for MONTHS at a time to try to run things with an overseerer. Varina got into a big fight with her brother-in-law, Joseph Davis, on the next plantation, and Jeff wrote and asked her how she could be so foolish, because even though Jeff was away, Varina wasn't her own boss. Joseph became the boss - of her and everyone.
One thing I took away from that book was, the husbands would routinely threaten the wives by isolation - not taking them to Washington where the social hub was. And then they would know they would be on an isolated plantation for another 6 months.
Varina wrote somewhere in her diary how sickened she was to visit other plantations and see children that were stamped with the Master's face because she knew that sexual relations were coerced. And Varina was always being compared to Jeff Davis' first wife who was Zachary Taylor's daughter, and who was apparently an ideal southern wife - never argued with Jeff or questioned plantation management or tried to do things unchaperoned like riding by herself.