Honey, you came to the right place. And it's not just Walt Disney's fault for your mono programming, hell, it's right in the Book of Genesis in the Bible, going back to around 1200 BCE.
"To the woman he said, 'I will make your pains in childbearing very severe; with painful labor you will give birth to children. Your desire will be for your husband, and he will rule over you.' "
If people were naturally mono, why did many men in those days have multiple wives? Why did they need to put words in "God's" mouth cursing Eve and all women by commanding them to desire only their husband, and for him to rule her?
Anthropological research is showing that humans used to be "promiscuous" in early civilizations. People would have sexual relations with multiple partners, and the children that resulted would be raised by a tribe, not a nuclear unit. Women didn't need to trade sex for economic stablity. Read Sex at Dawn, a book written for the lay public, to see the research done into the nature of human sexuality, before monogamy got a stranglehold on women so that men could determine biological paternity.
That said, I feel for you, as regarding not wanting to lose your monogamous husband! It's a big scary thing to transition from being mono to poly, there are hundreds of stories here about it. Read them and know you are not alone, and learn how to communicate your true nature. I had to do it too. Despite the work, it is so much better to feel authentic instead of living a lie.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 60) loving miss pixi (poly, F, 38) since January 2009, living together since 2013
also loving Punk (monogamish, 42, M) since Oct 2015
"Master," (mono, 34), miss pixi's Dom for 2 years