Greek Mythology is full of child abuse. Ouranos and Cronos both made a practice of imprisoning their children at birth: Ouranos threw them in Tartaros or shoved them back in the womb, while Cronos swallowed them whole. According to Homer, Zeus once flung his son Hephaestus off of Olympus, breaking his legs.
Greek mortals abuse their children just as often in myth. For example, Echetus gouged out his daughter's eyes, chained her in a cellar, and made her grind iron chunks to dust. Acrisius locked his daughter Danae in solitary confinement to prevent her from having children, and then threw her in a box and dumped her in the sea when she got pregnant from Zeus. Mythical women suffer various physical punishments and sometime death for getting pregnant out of wedlock, even when they were raped. Beating kids barely even gets mentioned in Classical Greece, except i.e. when comedian Aristophanes mocks moral relativists by depicting them as opposed to beating.
The case of Kullervo in The Kalevala. Oh boy, how he is abused as a child! In the end he becomes an Omnicidal Maniac and ends up in suicide. At the end of the canto, Väinämöinen especially warns of abusing the children, stating "a boy abused will never have the mind of a man".