Chord of the curse

I was whiling away a Saturday morning listening to Wagner's first finished opera, Die Feen — in preparation for my next book, Wagnerism, I'm going through the operas one by one — when a loud D-minor chord in Act II stopped me short. Namely, this:

Arindal, a king in love with the fairy Ada, has been put to a test: he must not curse his beloved, no matter what horrors she appears to have committed. When Ada seems to hurl their children into a flaming abyss, he fails...