First of all let me be clear that I am not judging you in any way with any of my comments. They are just observations from a viewpoint....mine.
Asking someone to consider a concept when there is no emotional involvement on their part, in a calm, quiet, detached and friendly spirit of "Let's explore this together" is one thing.
Asking them to explore that same concept when they are bleeding, hurt and angry is a whole nother thing.
Homo sapiens, being the sort of creature that we are, tend to strike back when hurt by someone. Not saying that reaction is right, just saying that is the reaction to expect.
Asking someone to put aside a lifetime of learning and belief systems is stretching the relationship at the best of times. I cannot speak for anyone else but I know my travel down the Poly path began very slowly and it took me quite a while to digest the info at the various stages before it all made sense to me. Think in terms of years before I was/am comfortable enough to feel secure and confident in the Poly lifestyle.
Asking that same person to put aside that same lifetime of learning and belief systems after you have just figuratively stuck a knife in their chest is going to have some predictable outcomes. None of which, I suspect, are calm, quiet acceptance and embracing the concept.
You have some very difficult choices to make here made even more difficult by the plethora of inputs coming at you. Your own, your wife, your g/f, society at large, the list goes on for a while. Open honest communication combined with patience is the only cure imho.