She will be infuriated. She will not have the other feelings you attribute to her, such as broken heart; sociopaths don't work that way. But she will be enraged.
She may contain it for a while; after all, she needs her family for a while longer. But she will excise them from her life just as she excised Caylee.
Because it's all about what people can do for her. If they can't serve her purposes, she has no need for them.
She won't "crack" until it serves her purposes. If it somehow benefits her--a plea arrangement, sentencing to life instead of death, and so on---THEN she may talk.
Don't make the mistake of attributing normal human emotions to her. She lacks them entirely. Everything you've seen from her has been a mask donned by a sociopath who, herself, is an empty vessel of entitlement.
ETA: Yes, Cindy was not tremendously warm to Casey, from what we've seen. But what we've seen is recent, end-of-the-rope stuff, when their facade was unraveling. I would maintain that any irrational or inappropriate behavior on Cindy's part was created by Casey, not vice versa.
Living with a sociopath creates a dysfunctional household--there is no way to get around that. And it is positively crazymaking for the rest of the family. I am (*ahem*) "normal," but can assure you that, while still under the roof with a sociopath, I exhibited some behaviors that would make most people scratch their heads. Take Casey out of that household, and give them some therapy, and chances are, you will find a relatively normal group of people, considering the tornado in their lives for 22 years.