My thinking is:
She stabbed him in the chest first; he stumbled to the sink, coughing out the blood, and she is stabbing him in the back; he turns to fend her off, gets stabbed in the hands, torso, maybe the head (over the eyebrow I thought there was a stab wound?), then seeing he is clearly wounded badly and dealing with a psychopath, the tries to get away down the hall; because of the stab to the chest, his legs give out which is when he may be "on all fours" like she said, screaming for help. Since she did not want anyone to hear him, that's when she slit his throat. Dragged him back to the shower, dumped him in it, then maybe used the cup to wash herself off in the middle of the bathroom (hence the water in the floor diluting the blood and wicked up into the bottom of the box), and runs the shower over him while she does that; she strips off her clothes, puts them in her backpack (sopping wet), dries off, gets dressed in the closet and takes all the bloody towels and the linens to the washer. Diabolical wench.
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