It is an expression which denotes affliction, feeling of defeat. It means disaster, the ultimate end, there is nothing else to do. Catastrophe, cataclysm.
Pronominal form enclitic of the past perfect indicative form of the verb to finish ("no more"). Used as a noun it is synonymous with final, usually abrupt and tragic.
COME ACABOSE:HABER ONE THING TO THE END; TO THE DISASTER.