Ava slapping Annika at the hospital — from her prospective, she was justified.
Yes, she should've apologised to Annika after finding out the actual reason behind everything that happened(I don't exactly remember if she did or not)
If Creighton hadn't force Annika to choose between him & her brother, all these things would've never happened.
But in the heat of the moment at the hospital, from Ava's point of view she had a valid reason to slap Annika. Ava was more close to the kings, she grew up with them, they were practically a family. She loves Creighton like her own brother. Seeing him fighting for his life in the hospital bed, she felt utterly betrayed by Annika.
I think everyone was right from their shoes it was a very complicated situation.
I don't exactly remember that if Ava apologised or not later, but I can't actually be mad at her for loosing her shit like that in the hospital.
It was pretty fucking messy.