You can't mourn something that was never alive to begin with — not since you've had them, at least. Their soul remains lost. And you were so close...
You will, however, mourn the time your ASSOCIATE spent stitching that body back together, only for it to be a complete waste. Alas, no sedative in the world can quell the BURST OF VITALITY that comes over a subject after the revivification process. The unbridled hostility is also an unfortunate side effect.
It was for the best that you ended this relationship with extreme prejudice.