At vindicta bonum vita jucundius ipsa nempe hoc indocti (or...revenge is sweeter than life itself)

"One sole desire, one passion now remains
To keep life's fever still within his veins,
Vengeance! dire vengeance on the wretch who cast
O'er him and all he lov'd that ruinous blast."

-Thomas Moore

"All the old knives That have rusted in my back, I drive in yours."

- Phaedrus (Thrace of Macedonia)