I – the Villainess in a Drama

How could the main character kill his beloved?! For sixty-four episodes I worried about every character, and in the end — such an awful finale! But it became even worse when, after a random electric shock, I found myself... in the world of the cursed series. And no, I didn't become the main character, unable to survive in a nightmare plot. I am in the body of her disgusting sister — the very one who is supposed to be killed even earlier! In my arsenal is only knowledge of the plot and my profession as an engineer. I need to get back to reality as soon as possible! But what is happening with the main character? Why is this incredibly charming jerk always hanging around? Has he forgotten that he is supposed to be in love with someone else?