What stood out most saliently in what you have written is the "panic attack". I recommend examining what that was in minute detail, very closely and carefully. My intuitive hunch is that you have fear around opening your heart, and the whole mono vs poly angle isn't really the big deal it seems to you to be. It is more likely a distraction.
That same fear would almost certainly arise in a mono context, with your heart opening big. Right? I'm right, aren't I?
I know about these things. There's only one solution. You must learn to dissolve the door to your heart. Aren't you tired of it yet?
Breathe freedom and love and joy into your heart each day. Seriously. Make a practice of it, daily. And love freely, as much as you can -- with friends, with acquaintances, with strangers. Give love and receive love as much as you can. Let go and fall into its blessed arms. Come back home to your true life.