I cast mini-nuke

So I underestimated how powerful the fireball spell is in 5th ed. My players are at 3rd level and got a scroll of cast fireball two encounters back. They are facing 6 orcs, one boss orc at 30hp and one ogre at 63 hp.

The wizard on the first turn (a surprise round) incinerated five orcs outright and left the boss at 6 hp. I was livid.

Me: “This is the D&D equivalent of a mini-nuke.”

Paladin: “Blame the fireball man not us!”