After Cindy's first phone call with Casey in jail where Casey made it clear she didn't like being mom saying she was unclear about Casey's involvement I think we have seen Cindy reeling/melting down/and in denial.
We know on the third of July Cindy felt punished by Casey taking Caylee from her, and she felt it was undeserved. Her wild and illogical statements about the kidnappers/we know who has her/this is a missing child case/look for all seem like submissive posturing to Casey. Casey, who if there is a one in a million chance Caylee is alive, has the only ability to tell her where she is. I don't think Cindy believes the nanny story at all, but wants/wanted to believe there was another story and if she did all the "right" things, said Casey was being brave and mother of the year, and that she believed this fairytale maybe Casey would stop punishing her and bring Caylee home.
Yes logically she has to know something horrible happened to Caylee, but if you don't have a body yet it is totally normal to cling to the what ifs. If your child was missing and they told you statistically and circumstansially we have to think they are dead, and it made sense on every level logically, but they couldn't give you a body how long would you hold out hope that they were wrong? That is how victims families get taken advantage of by people who prey off of that hope. I feel horrible for everyone that Casey has involved in this.