How could this be possible EVER (ending, obviously)

What a mess on an ending. The kid blows up the house, the mother gets consumed by fire (we even see how the fire reaches her), just to be ALL ALIVE AND WELL after hospitalization?! Not only this, but AFTER THREE KILLINGS and one failed attempt THEY SET HER FREE?!

WTF filmmakers? Are you really think we're all idiots?! Just to make 'surprising, shocking ending' (pfffff) you let everyone forget that the woman killed THREE CHILDREN, and even THEIR FATHER says: "she wasn't herself that day". What kind of argument is that? And how even such father - after abandoning his children for sure death - can tell his sole survivor son that "they gonna live with mommy again". How can he even dare to expect his son to accept this?

Terrible, idiotic, unrealistic and simply cheap ending, lack of logic and sensitivity.