Cindy knows the truth, she knows Casey killed Caylee, and she knows why. Cindy's problem is that she doesn't want anyone else to know / believe this uncomfortable fact. I think that whatever Casey does is a reflection on Cindy in Cindy's mind. Cindy was a good mom, therefore Casey could not kill her daughter. If Casey is guilty, then Cindy is a bad mom, if Casey is in prison Cindy's a bad mom, and my god ... kid on death row = bad bad bad mom.
So Cindy could probably handle having a bad kid if that badness was contained inside four walls because then it would be Cindy's own problem, and she could choose how to paint the story to outsiders, but this one is off the hook ... this is all about 'face'. Cindy can't stand losing face so if she can try and weave her own version of events which paints Casey in a different light then her role in the drama can be something palatable.
I think this is why Cindy is so desperate for Casey to show her a sign of affection, because at the moment it's going this way;
Casey hates Cindy, she hates Cindy so much that she killed her little daughter just to knife her square in the heart, everyone else hates Cindy too, the world hates her, this is all her fault. Cindy is a bad mom, Cindy didn't protect Caylee, Cindy is bad, and partly to blame for the death of Caylee ... this is unbearable.
And Cindy doesn't want to be the bad one, Cindy wants some leeway, Cindy wants some sympathy, so Cindy's going to act a little bit nuts, and then everyone is going to cut her a bit of slack, and not look too closely at the history she created, and the events that led up to the death of Caylee, and at who Cindy really is.