At the end of the game, I chose revenge and so Kate got killed. I popped Peggorino between the eyes for revenge, and got the achievement for completing the game.
After the credits rolled, I walked out of the wooded park where it all went down and got a phone call from an "Unknown Caller." I answered and lord behold it was Kate. Damn, that chick can take a bullet like a champ. Apparently she's not dead because we just had a nice night out at Cluckin' Bell.
Even the Zombie Kate won't sleep with me though. It's probably a good thing If you get bit by a zombie you become one, but what if you have sex with one? The sharing of bodily fluids sounds dangerous.