I truly hope you figure this out. I don't think I am the best source of knowledge about this, because my own experience is so heavily dependent on one thing. I have never loved someone the way I love Redpepper. That is the deciding factor. If my ex-wife would have mentioned wanting another man, I would have left her immediately.
I honestly wouldn't recommend a mono/poly relationship to very many people, especially a long-distance relationship, so I would be of little aid to your situation, I'm afraid. Sorry. I have posted benefits and pitfalls on other threads, however.
I hope you all find happiness and love.