You ask me, “Why did G‑d allow it to happen?”
You recognize that everything in this world has purpose and meaning. Examine any aspect of His vast Creation, from the cosmos to the workings of the atom, and you will see there must be a plan.
And so you ask, where does this fit into the plan?
How could it?
I can only answer, painfully, G‑d alone knows.
But what I cannot know, I need not know.
I need not know in order to fulfill
that which my Creator has created me to do.
And that is, to change the world
so this could never happen again.
(The Chabad Rebbe, Menachem M Schneerson)