"So ... How have you all started realizing that you were NM/poly/swingers/open/etc.? Are you with a partner now that you were once monogamous with? Did you both become NM together? I want to hear both the good and the bad stories."
If you want to hear both the good and the bad stories, I recommend the Life stories and blogs board
. You will probably find the answers to a lot of your questions there.
As for me, I went through a period of change/rebellion that lasted about ten years, and by 2005, I had put aside virtually all of my previously conservative beliefs. So I was in the right frame of mind to be introduced to poly, and it was around that time that I fell in love with someone who was already married. She did a lot of research on the web and found out about poly, and things slowly evolved to where they are today: a polyfidelitous V, where she has a romantic relationship with both me and her husband, and her husband and I are platonic friends.
I hope your situation works out, and that your SO will stay with you. Perhaps both of you will decide to live a poly life.