Me too. Also, to a numpty like PF, it might have been easier to explain the non-fatal coffee poisoning -- lack of precision with dosing, not everyone responds the same to meds, a front stoop isn't a hospital room, so I couldn't really stand there and watch to make sure she drank it all, etc -- than somehow failing to kill KB with a metal tube or bat.
I'm not even sure that KK's goal in this was to eliminate, through murder, a rival. She'd already had years of practice with PF's bizarre "loyalty tests" -- paying for the gifted dog, having a termination, trucking out to CO for a shag, so maybe she thought she could defeat KB in that way. Prove that she was his best girl, blah blah blah.
Can't pretend to make sense of her actions and feel she is likely to be one of those people that can justify nearly anything. It's the driving out one last time to clean up a murder scene -- another and particularly vicious test of loyalty -- that is truly baffling. And yet over and over we see friends and families help out with a "disposal" at enormous cost and risk to themselves. Why does anyone do it? Why did she?