Yeah, Koto has been cycling through the would've, could've, should've, and what ifs of her relationship to Aya for 7 years, only for the focus of that brooding to come back exactly as she remembers. The unreality and fragility of the situation, along with the fear of losing Aya again, has to be incredibly nerve wracking.
Aya, is pretty much doing her best to find a place to fit in in a world not exactly of her time, and is pretty admirable for how she's handling that.
Erika, on the other hand, is pretty awful considering that she seemingly wished this trauma on two people that are supposedly her friends because of her own jealousy and inability to move on.