Melinda becomes a great big woobie once you realize why she's so quiet and isolated. Everyone hates her for what she did at the party, and Andy (the cause of her suffering) is the Jerkass of all jerkasses to her, knowing quite well that she won't fight back.
And then it comes full circle when Andy decides to go for a second round.
Melinda's rape, and how!
The movie version cranks it up to eleven, where you can hear Melinda's muffled cries as Andy rapes her.
The scene where the school principal, the guidance counselor, and Melinda's parents are trying to figure out why she's been skipping school and why her grades have slipped. What especially stands out is when her father angrily asks what happened to his once cheerful and studious daughter to make her act this way.
The scene where Mr. Freeman rips up the painting he had been working on for much of the school year. It even makes the rest of the class gasp in shock.
Melinda finally works up the courage to tell Rachel that she was raped during the summer party. Rachel initially believes her and is accordingly horrified, demanding to know who did this. When Melinda admits that it was Andy, who Rachel is currently dating, Rachel immediately turns against her and accuses her of lying.
Further, the implication that this was a reflexive response on Rachel's part, and that deep down she does believe it and is sickened and horrified by it.
Rachel:(to the librarian) I'm going to the nurse. I think I'm going to throw up.
The implication that Rachel and Melinda's relationship might be beyond repair. Rachel breaks up with Andy after he makes her uncomfortable with his behavior during prom, and inadvertently reveals Melinda had told her previously that he was a sexual predator, driving him to attempt to rape her again. Afterward, Rachel heard about it and left a voicemail asking Melinda to call her. Melinda doesn't say if she answered or not.
On her last day of class, Melinda starts crying as she hands in her finished project. Mr. Freeman tells her that the salt in tears ruin art materials, gives her an A+, and says, "You've had a rough year, haven't you?" This invites her to open up to him.
