From an interview with Alice Sebold that is published as a supplement in the back of the book:
Question: People often wonder if writing is therapeutic. If you’re writing about a trauma, does that help the pain of the trauma recede? Susie in the novel [a different book] says something like every time she tells her story, a drop of the pain goes away. But as a writer who’s written about your own trauma and then written a fictionalized version of a similar trauma, is writing therapeutic or do you think that that’s really the wrong way to approach it anyway?
Answer: My feeling is that therapy is for therapy and that writing can be therapeutic, but therapeutic writing should not be published. My job as a writer is to go through the therapy myself and, if I manage to get through it and I feel I have something to share from that, to share it with my audience or my readers. But I don’t write novels and seek to have them published so that I can get therapy from having written them. That’s really the responsibility of an individual to do outside the context of their published work.