Welcome to our forum.
I obviously consider poly to be a viable possibility, but you have to decide if it's right for you in your situation.
"I didn't exactly pick the best person to develop an attachment to ..."
What are your concerns in that area?
"... it's totally uncharted territory for us ..."
Continue to read and post on this website, and you will get more information and wisdom about how to proceed. The Golden Nuggets board
might be a good place to start.
"... jealousy is a real thing ..."
Perhaps one or more of the following links might help:
Let us discuss the greeneye monster shall we?
How to slay the greeneyed beastie.
Jealousy, Envy, Insecurity, Etc.
How do you achieve compersion?
The Theory of Jealousy Management
The Practice of Jealousy Management
Jealousy and the Poly Family
Kathy Labriola: Unmasking the Green-Eyed Monster
Brené Brown: the Power of Vulnerability
Glad to have you with us.