I don't have much advice, but I do have all the sympathy in the world. I'm sorry it happened and that you're hurting, and please find someone to talk to - a professional, a trusted friend, a family member, anyone. No one should grabble that alone.
And dude, it is OKAY to feel and to say "I am furious and hurting, but I do love you and wish you the best, so I'm gonna extricate myself from your lives because this hurts too much". It's okay to feel all those conflicting things, and most listeners will understand that. You don't have to simplify or edit your story when you tell the professional/trusted friend/whomever.
Good wind.
Maybe this is just me and my culture being weird, but is there that much difference between "potential friend" and "potential squeezebuddy"? Especially since it sounds like you tend to go for "friendship which might or might not turn into something more".
So why not just go for the friendship? And then have a "three conversations, then evaluate" for yourself - meaning that if no boyfriend has been mentioned in three conversations, and everything clicks, try to go for something more.
Or is your problem that you're not sure how to do the "friendly without playah overtones" thing?
I'm thinking that a girl who identifies as poly has done enough relationship-thinking to be able to have an honest and open conversation about compability. But maybe that's my unshakable faith in humanity seeping through