Women in White (Weeping Women)

It's a ghost story. Well it's more of a phenomenon, really. 
They're spirits.
They've been sighted for hundreds of years, dozens of places :
in Hawaii, in Mexico, in Arizona, Indiana...
All these are different women, but all share the same story:

When they're alive, their husbands were unfaithful to them,
and these women, basically suffering from temporary insanity,
murdered their children.

Then once they realized what they had done,
they took their own lives.

So now their spirits are cursed.
Walking backroads, waterways...

And if they found an unfaithful man,
they kill him.

And that man is never seen again.