Not Just Friends — Peri Elizabeth Scott

In a post apocalyptic world, a woman struggles to survive until reunited with her son, only to bring grave danger to the small band of people he leads. Choosing to sacrifice herself to protect the clan, Ann Murdoch discovers how resourceful she can be in the face of torture and death.

She knew revenge was a luxury even as she yearned for it, her daughter horribly dead at another's hand. She herself killed a boy, albeit in self defense, and obviously someone connected to him doesn't view luxury in the same way. And that someone is well past the yearning stage…