I saw this essay cited in the nonfiction-advice book Tell It Slant, which I found quite helpful, so I looked this up. If you can't decide between your family's love or the millions of dollars your thinly-veiled tell all fiction memoir will garner you, Mimi Schwartz has some thoughts. For instance, it's never good if you're writing just for revenge:

If the main impulse is self-disclosure, it's best to resist these stories, says poet and essayist Stephen Dunn. They are often 'the kind that should be put in a locked cabinet, like diaries, kept, if at all, as private data for our children to find after we're dead.' How to tell? If the motive never shifts from confession to exploring the story's subject matter, the work will be insufficiently transformed and include details for the worst of reasons-because they happened. 'The too naked poem,' Dunn warns, 'the one that makes dirty laundry its flag, which never gets beyond its original impulse' is a poem we have failed. We should hide it from everyone."

More on when, and when not to write about family here.