Hi Confused - and thanks for sharing.
From what you've written I'd maybe just toss out a couple comments.
First - I'd just go slow - acknowledge the new discovery you've made and try to get you and your sweetheart talking about what it all might mean. Don't be rushing to "label" anything or leap off in any crazy direction right off.
Explore together, learn to talk about potentially sensitive issues etc. It can only benefit your relationship long term regardless if anyone else enters the picture or not
Secondly, I'd encourage you both to dig into understanding the whole "jealousy" thing. Jealousy is a very negative and dangerous emotion, even if it seems to be built into us. It can however be banished to it's dark corner and told to stay there. This is just another thing that will benefit your relationship regardless of whether you remain monogamous or drift towards poly. It's still a dark demon that deserves banishment and there's loads of good resources and people that can team up with you on that quest. Lots of good reading material already right on here and some great people anxious to help. So don't be hesitant to call out.
Good luck - be happy.