It just doesn't matter, your so called "friend" could erase you from timeline because she was horny, she also broke her promise to you to not go after your mother. Even though she didn't initiate, she didn't even try to stop her either. I'm fine she is in the story but not as friend. She could be main villain for Lucifer's sake. I would despise MC if he forgives and welcomes her into his life. She just played Russian roulette by pointing gun to your head. No sane people do that to their friend.
Hey cool, you have your opinion and I appreciate that - nothing wrong, all good.
For me - the Dev made pretty clear that MC's mother had a traumatic experience (meaning she was dumped after finding out she was pregnant). Emotions run high, and she looks for consolation, they hug and one thing leads to another - I can see how Kim could make the mistake (knowing that MC's mother is already pregnant with MC and sister). While in 0.2a the whole pacing of that lewd scene is off (I cannot see how Kim could garner so much trust in so little time )
The literary conundrum is that even though Kim made a mistake that would be hard to forgive - it led to provideing MC with everything he ever wished, stable family with solid income, happy and loving mother which makes it hard to hold a grudge.
Additionally theirs is an abusive friendship - with Kim an actual bulldozer plowing ahead, dragging MC in her wake (as he's an obvious mid/low level beta male - I think only the MC douchebag from "Double Homework" is a lower Beta) Having witnessed such relations IRL (thankfully not suffered) the depiction here is utterly believable.