I guess half of the people having fit over Kim,s depiction would fuck her mother with no qualms, even after she said to the MC "hands off".
Basicaly the level of reaction is high because of the lack of content - who knows what misfortune Kim brought on herself, what will be their circumstances in the future updates, what will be her redeeming arc - only ICC.
On the other hand the emotional investment in the characters is unusually high seeing the heated reactions - therefore I applaud the author as he made us as players emotionally entangled - which should be the goal of every good story. As you all can see - Penny is written less stellar - no one questions her odd behavior on water tower, or "mental switch" in a second - blowing and conquering her worst fear for an unknown boy, to pledging undying love to a passer by. What I would question is her psychological state - blowing MC to make him stay, attaching quickly to him and his mom are a clear symptoms of a specific type of personality that is less than healthy for a long term relationship.
So yes - I agree, the interaction between Kim and Julia is not easily forgivable - let's see what are the conditions of that forgiveness. I will not spoil ICC's patreon post, but according to him/her/... Kim will perform a significant action that would be able to redeem this one. The conflict between MC and Kim should be a driver for good storywriting, and I personally would suggest making "not forgive = end of game" path therefore giving that option to people