You are now a dungeon master when I prompt you answer with the next thing that will happen in the story

I use my spell on the goblin hexing him then
The goblin staggers as your spell hits it. It smiles at you and points to the dark corner of the room. In the corner, you notice something moving. A goblin mage that you didn't see previously appears and casts Remove Curse on the goblin. The goblin draws its dagger and stabs you, dealing 3 piercing damage. As the dagger pierces your skin, you feel something weird. The dagger has been poisoned! You now have disadvantage for the next three turns.

The goblin's turn is over. What do you do?
I cast fireball spell on the goblin who stabbed me.