Until I see evidence against P, I think he picked his child up, returned to the ranchette & something went down @ the condo. Did he prearrange it? Or did a scheming, scorned woman?
If P/KK had a romantic type relationship in the past, at some point, it ended. Maybe, when she married?
But, from what we think we know, her love/obsession did not end. Owning horses together indicates (to me) they had an agreement to be friends. We’ve all ended a relationship & say, “but, we can still be friends”. Perhaps, KK thought she’d once again be the object of his desire.??
Then, KB arrives on scene. Then a baby. Now, P is even busier, has little time to hang out. Not a stretch to consider KK was mad enough to kill.
Set the stage....start telling the bestie P wants this & that.
When this & that happens, she thinks her butt is covered. Her bestie knows P wanted KB dead! Plus bestie told her boss, an attorney.
Of course things go wrong. After all, she’s a nurse, not a mastermind criminal. So much to do. Turn phone off, turn on, send texts, eat at Sonic, clean up....all on no sleep, after a long adrenaline fueled drive.
FBI questions her, she flubs up & now is really petrified (with good reason) & self admits to a med’ facility.
Speculation only