Disturbed beyond belief

I would venture to say that Chapter 16 in The Handmaid's Tale may very well be the most disturbing chapter of any book I have ever read. It was painful to get through to say the least. With that said, I ask myself why exactly did I find it so disturbing. It isn't because it is a sex scene, that much I can stomach. It isn't quite a rape scene, though it may be borderline. I think what truly made this scene so utterly disturbing is the vivid description, especially of Serena Joy. It is easy to sympathize with Offred, after all she is receiving what some would call the "physical" brunt of the abuse. But what about Serena Joy? What choice does she have in being present for the ceremony? Being present for her own husbands infidelity? A thousand cigarettes, and hours of allowance to a tv could never begin to offset such emotional abuse. I can't help but bring myself back to these certain lines over and over: "My arms are raised; she holds my hands, each of mine in each of hers. This is suppose to signify that we are of one flesh, one being... It may or may not be revenge." and ""Get up and get out..." There is a loathing in her voice, as if the touch of my flesh sickens and contaminates her." These specific lines make me wonder what exactly is the ceremony signifying to Serena Joy. Is she merely jealous, or does her hate stem towards her own husband for being so despicable. The novel, I suppose, will reveal such, but as of right now, this scene left many emotions a mystery, especially on the end of Serena Joy.