Well, it wouldn't be poly if there isn't consent, so it looks like you have a hard choice to make.
Can you invest in your marriage and make it the best expression of partnership and love it can possibly be, even if it continues to be monogamous?
Or is living polyamorously something you absolutely must have, enough to leave the marriage and seek it elsewhere?
What is it you hope poly will bring to your life? Are you dissatisfied with any elements of your marriage (besides the issue of her not wanting poly)? What prompted your seeking it out?