I keep thinking about this case. Mercifully, the facebook page has been removed.
What comes across is that the mother seems to have a true affection for the child, and grieved while and after she suffocated him. In the way you would say "I dearly love the family lake cabin but I just can't manage it anymore, I have to get rid of it, I can't do it anymore". Or "as much as I've loved my involvement in wildlife rescue, I just can't do it anymore. I'll miss it terribly but I just can't manage it".
Her disconnect is just . . . so shocking. As much horror as we see on these forums, this particular case is shocking. You could see it developing on her facebook page - beginning with the post that said how much she missed the days when he couldn't move around. She doesn't seem as clearly insane as women who hear God telling them to kill their babies, or believe their babies are inhabited by evil, but there is a cold rational callous disconnect here that . . . is just baffling. By all accounts, he was a normal, healthy, pleasant baby to be around. But even before he was walking, he was just too much work and she made this cold decision - with this weird affectionate ceremony - that she couldn't do it anymore and it was time to kill the baby she honestly liked. This is a harder notion to understand, IMHO, than a monster boyfriend who beats a boy to death over a toileting accident.
Maybe because in those cases, you see it coming a LONG way away so it can be prevented. This? No one seemed to see it coming.