Polygamy in Nauvoo

I did not know Joseph Smith was a polygamist. I was made out to look pretty stupid in front of people when the church that I believed so heavily in wasn't telling me the full truth from the very beginning. When I read that I was shocked that nobody had ever told me that before. How could I have taken a history class of the church and that was never brought up? Why was I defending Joseph to friends and that weren't members about him not being a polygamists when he was? And then I watched um what was it? Waco on Netflix and watched David Koresh and I was like whoa wait a minute this man is a modern Joseph Smith, why