Beloved: The CREEPY kid

Well, obviously Beloved is the fourth, and by far weirdest, child. It is also obvious why she is not included in the home address of 124. But what I do get is why did Sethe begin to lose it (her mind) after Beloved's ever growing need for things such as ribbons and candy grew? Why spoil her so much? Yeah, sure Sethe KILLED her, but so what? It's not possible to make up for what was done. And I understand that Beloved is a child in a teenagers body, but does she REALLY have to make those faces and drool so much? Kudos to the actress who played Beloved.