I wouldn't get divorced unless you knew you would still get all your benefits. It's so drastic and affects everything, including insurance, filing your taxes, and so on. Besides, you're just starting out and looking at exploring polyamory. Getting divorced now is kind of jumping the gun, I think. Who knows what could happen? You both might find that poly does not really work for your relationship, but you'd be divorced. I think dip your toes in, slowly, under the radar, take baby steps, and do not come out about it. And after a time, a few years down the road, if/when you've established good, solid poly relationships that you can count on, then discuss if proceeding with divorce would benefit you.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein