I think what I've learned about people's reactions to my mono/poly marriage is that it always comes out of "how they would feel" rather than my actual circumstance or how I feel. Projection is almost always the default response because people tend to try to put themselves in your shoes.
For example- People who have been cheated on assume I'm being cheated on.
People who have endured emotional abuse think I'm being emotionally abused.
My best friend's response (a nurse and a christian) was to give me an STDs AND a Bible lesson.
I have come to terms with the initial response almost always being negative and out of projection. Sometimes I address it briefly. Sometimes I ignore it. And in the end many people get their heads out of their own *space* and are finally able to ask you how you feel in your unique circumstance.
My best friend finally came around and even apologized for her initial response.
So, I don't take the initial response as "the response" anymore- just a hurdle to get over for true understanding.