Brutal murder vs mom pushed over the edge? [tigger]

Scenario: Woman is a stay at home mother, lives in a abusive household with her husband and thier 7 month old infant. She had been abused for years and possibly suffered some brain damage after one beating before the child was born, because she rarely spoke and had "concentration issues" after it happened. Meaning she was dangerous driving and it was hard for her to read. They're a fairly well-off family but the husband insists on her raising the baby without help while he works. On a nanny cam in the house the mother can be seen sitting on the floor, watching her baby wiggling on it's stomach and fine on top of a blanket. The mom suddenly grabs her childs feet and repeatedly slings her into the floor. The mom can be seen sitting for a few minutes silently before calling 911 and trying to explain what she did. Then she sits the phone down with dispatch still on the line while she gently strokes the child while crying. Child was gone before EMS arrived and the woman was begging/asking them to not call the father. What do you think? Was she so pushed over the edge and abused that court should go easy, or should she be locked up forever? What should her punishment be, if any?