I'm with MonoV on this. It's not necessarily that he needs to deal with his jealousy, it's that he just doesn't want to share.
When I have an ice cream cone and some stranger is eyeing up my ice cream, it's not "insecurity" that I don't want to share. It's that they can go get their own damn ice cream, this one's mine.
Of course, ice cream cones don't have feelings, so it doesn't mind that I'm being possessive of my ice cream, because I actually do possess it. Your boyfriend does not possess you.
One thing I will tell you is that you're not being a selfish cow. Every person has the right to attempt to live their life the way they want to. Circumstances don't always allow those attempts to be successful, but that doesn't mean you can't try.
Your feelings are very natural and valid for a poly-wired person. Really, the only problem here is that you happen to be in a relationship with a mono-wired person.
What you'll need to decide, one day, is whether you can live with yourself if you keep repressing these feelings. There's nothing wrong with telling your boyfriend that you need to explore this side of yourself. Just be prepared that he may not stick around to see how it works out. But if it were me, I would have to be true to myself and do what I feel I need to do. If he's not a part of that, then it's not meant to be.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker