Character Arcs and Disbelief

What I'm reading: Silencing Sam, by Julie KramerMy current writing obstacle: character arcs. A character has to change over the course of the book. My heroine begins as woman who's fled her abusive husband, taking their son with her. Her 'inciting incident' happened before the book opened, when the husband started beating the son as well, which was her last straw.Ultimately, she's going to have