I think they definitely killed the King. Cora’s plan all along for Regina was to kill King Leo–before Regina pushes her in the mirror she talking about how the “the king is not a strong man.” Although, Cora taught the Red Queen I think Cora was the “real” power in Wonderland and influenced Ana to be the selfish queen she is. Cora, I think took Ana under her wing, and tried to use her to fill the emptiness inside her from Regina. I know Cora, didn’t have a heart but I still think she was “hurt” that Regina pushed her away “literally.” However, when Hook came to WL, I think Cora left without a good bye or any really thought to Ana. Then Ana was the ruler and then along came Jafar.