If a Book Falls in the Forest ...

Feedback from a few beta readers has given me pause.
They are reading a draft of Reston Peace, a novel I’ve been working on for many years.  Each time I’ve handed it over to a reader, I’ve given the disclaimer that this is an intense novel.  It is about sexual abuse, sexual addiction and recovery.  It has strong language and explicit scenes.  It is not for everyone’s tastes, and all I ask is for honest feedback.
My beta readers have given me nothing but.  They’ve told me that, while the storytelling is powerful, the topic itself is so unpleasant that it is a difficult book to get through.  One reader said that while I’ve written an accurate depiction of abuse, she questions who would want to read it.
Which raises the question, if a book isn’t readable, is it still a book?
If I’ve written something – no matter how realistic, no matter how “artistic” – yet it has a limited chance of finding an audience, does this mean I’ve been wasting my time?  Do I need to tone it down?  Do I need to reimagine the story in a more palatable fashion? 
If the story pushes the reader away, makes her become detached from the emotions because it is too intense, am I doing a disservice to the reader?  Are my expectations for what a person is willing to read too high?
I know my intentions.  I know that I am going for honesty and directness.  I don’t want to shy away from the topic.  I don’t want to couch it in euphemism, nor do I want to put the abuse in the past or leave it offstage.  I want to hold the camera, as it were, on the awful moments so that they have immediacy and impact.
Of course, this is a work of fiction.  Even if I based it on actual events, it is still a work of fiction, so I hesitate to state that this is an accurate depiction of abuse.  It is foremost a story, contrived and constructed.  But within those limited parameters, I want to give an emotional resonance to the experience.
Yet have I gone too far?  If the topic scares away readers, then who will be the audience?
It’s a fine line to walk – staying true to the integrity of the original vision for the novel and giving the readers something they can enjoy. 
It’s a tough lesson to take – that something I’ve worked on for years may not find the audience I hoped for.  That the story needs streamlining and yet more revisions.  That my choice of topics may not be palatable in its current incarnation. 
And it’s tough to trust my own artistic vision when it is clearly at odds with the views of several readers.  This is why writers put in disclaimers in their acknowledgments: “Thank you to all my editors, readers, experts who helped with this work, but any errors or mistakes that remain are my own.” 
So here is my preliminary acknowledgments for as yet unpublished Reston Peace:  “Thank you to my beta readers for putting forth the tough questions and challenging me to grow as a writer.  No matter what happens with this book, I will continue to wrangle with the best way to tell a story.  Artistic vision and reader enjoyment are not mutually exclusive territories, but finding the common ground will always be my intended destination.”