Hello! You asked for quotes about sexual abuse in The Chrysalids.
While there isn't any definitive or specific sexual abuse in the novel, it is hinted at. Gordon, the so-called Spider-man of the Fringes, takes a fancy to Rosalind. Even though Sophie is in love with Gordon, she is barren, and cannot give him any children. Before she was banished from Waknuk, she was rendered infertile by the authorities. Here are some quotes which illustrates that Gordon is willing to take Rosalind by force if necessary. It is part of a conversation between David and Sophie.
"He wants her, doesn't he?" she asked.
"That's what he said," I admitted grimly.
"She could give him babies?" she persisted.
Here's another quote from Rosalind, this time, about her fear of being raped by Gordon.
"I'm frightened of him. He's a different kind. Not like us. Not the same sort at all. It would be outrageous-like an animal. I couldn't, ever...if he tries to take me, I shall kill myself..."
Thankfully, the rape never happens: a battle rages between the people of Waknuk and the Fringe people; both Sophie and Gordon are killed in the battle.