Well, take the time to heal your marriage. That comes first. I am concerned about two things here
- That she would spring a Big Conversation on you like that, at that time. That's poor sense of timing.
- That you would let yourself get startled into a "yes" and then have a cow later because the "yes" you said was not a real "Yes!" If you were startled, what stops you from saying "Wow. That is startling. My initial impression is yes -- I am willing to talk more about that. But this is not the best time and that is much Bigger Conversation. Let's make space to have it well."
Second? That's good that you noted that one person has a bad history with their secondaries. You don't need to get mixed up with a messy person like that.
Third? You know that you can try it on without her actually
having a lover right?
Read poly websites together. Read posts on this forum together. Try it on.
- "What would YOU do if that was happening to US?"
- "How would WE handle that situation? How would you expected to be treated?"
She may be more willing to go to THIS point -- "Wife, I'd like to explore the idea safely. Would you be willing to read poly things with me? And just talk about it? Not run out to have a secondary relationship, but just try it on in Mind only?"
Then only thing changing then is you two trying to develop greater understanding each other, develop better communication and be more Open TO EACH OTHER. But just to that point for now. Maybe that's all it ever gets to. And is it a horrible thing to know yourself and your wife more deeply and enjoy each other that way in your monoship? No, it is not.