What happened to Osha?? I can't remember.
Anyways, this episode revealed so much about Littlefinger, summed up nicely here:
“You gave me those drops and told me to pour them into Jon’s wine,” she blurted out, confessing that it was she who killed her husband, Robert Baratheon's original Hand of the King. “You told me to write to a letter to Cat, tell her that it was the Lannisters who…,” she added, confirming that she stoked the flames of discord between the Starks and the Lannisters. Which leads to the rather marvelous, and game-changing, revelation that Littlefinger has singlehandedly masterminded the events that led to Ned Stark’s death, the War of the Five Kings, and the near ruin of Westeros, not to mention Joffrey’s assassination and the kingdom’s inattention to the quite serious wildling/white walker problem. In short, he’s been behind nearly every major power shift throughout the entire series.