I almost get the sense that what you're really asking for here is support to do what you feel you need to do, which is leave the marriage. It's relatively clear that your relationship styles are incompatible. She will never be happy with your polyamory, and you will never be happy without it. The decision may be easier if you look at it in those absolute terms. Instead of thinking "How long do I give her to come around," I would be thinking "Am I prepared to live like this for the rest of my life?" If the answer is no, then you're only prolonging the inevitable.
How long is too long? Well, forever is too long, and it seems to me you're looking at forever...
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker