For those who hate sooah, i wonder if the story would have started fromher perspective and...

Having gone through something traumatic in no away excuses one becoming a toxic person. Being hated(as in strongly disliked) for hurting other people is only a reasonable outcome, being bullied/hurt/harrassed in retaliation is not.
It's up to each individual what capacity for understanding they have toward someone who's hurt them, especially when they don't know that person's situation.
On a personal note, even knowing about her trauma, I still have no sympathy for someone who uses her mistrust as fuel to harm others instead of trying to at least contain it to herself.

I do agree with u but expressing ones feeling is a learned behavior while one person learns to be forgiving from their family, environment, etc. the other learns to do the opposite. i just don´t think it´s as simple as that for someone to act in kind when they never had a chance to learn it. sometimes we make everything sound so simple when it´s not. again i´m not excusing her behavior, it´s just we don´t know her back story and her perspective.

remember the chapter when she got upset at mirage for saying she is not dating the white hair dude but then from outsider´s perspective it seemed they were very close and sooah though mirage is making fun of her? we are seeing everything from mirage´s perspective and we know what she is thinking so we know she was being genuine, but what if we could not read mirage´s thoughts?

u don´t have to agree with me, i just feel that our perspective would have been different if we could only see things from sooah´s perspective. oh god i type so much lol my poor fingers

Of course our opinion of someone could possibly change when we look at a person from different perspectives and with more information..
What difference will it make knowing that Sooah had a past where she was bullied at school and at home, had hardly anyone to rely on and to trust while growing up? We will understand the causes and symptoms of her trauma, which will explain her behaviour, to a degree.
However, manipulating and mistreating others is her choice. She is jumping to conclusions that are triggered by her lack of self-esteem and loneliness and proceeds to act rashly and harmfully based on those. She's lived long enough and has the experience to know how her behaviour affects others. At this point, she's no better than those who bullied her.
Where I'm going with this is: people who go through hardship should be supported and treated appropriately. However, unfair as the lack of the above in a timely manner may be, they still need to be held responsible for their harmful actions (see bullies/school shooters/murderers who were once victims themselves).
Sooah of course has the potential to overcome her trauma and treat her disorder, but the will to change has to come from her, even if she has to go through it alone since she's an adult. Does that mean people shouldn't hate her for being a toxic person and hurting them? No, she's done enough to warranty hate from them. That said, it's up to her to change and to other people (except for victims of her behaviour) to be open enough to see the change in her.