Oh that poor, poor woman. How utterly dreadful to survive when your dd has been killed.
ABD, I know you always try to argue the male point of view, but there is no reason - yet - to say he had been 'pushed beyond breaking point'. That suggests someone else - his wife - is to blame for his actions. Adults are entitled to end relationships without fearing that the other parent will be so vicious they murder the child.
I honestly think it's ruddy unfair to most men, especially separated or divorced parents, to bracket them with this sort of crime. (Although obv. we have to wait and see what comes out of the investigation, of course.) It is possible, for instance, that he was a violent man and his wife had left in order to escape his beatings, rather than him being 'pushed beyond breaking point'. We don't yet know. But the most dangerous time for a woman who flees from a violent relationship is when she ends it.
Family annihilators (if it does eventually emerge that he falls into that category) are violent, savage people who would rather murder their children than lose control of their family. Mostly men although not always. There is a distinct pattern of behaviour leading up to this act that makes them quite different from the sort of parent who acts in despair, from mental illness or imagining they are sparing their child from suffering.
Anyway, all the public definitely knows at this stage is that this is a horrible tragedy that has some hallmarks of a family annihilator. And that this poor woman will suffer the most terrible grief for the rest of her life, God bless her.