Welcome to our forum.
I would recommend lots of reading and posting on this site. Note that you can do searches and tag searches as well. All of these things will help make polyamory more familiar ground to you, which will lessen the fear factor.
As for tackling jealousy and insecurity, I have a few links you can follow:
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
Only time will tell if this is something you can handle. It's great that you're willing to give it a try.
Hope you enjoy your stay amongst us.