I think it's important to realize it make likely take some time to adjust to such a huge shift in perception. Especially if you had a monogamous deal with marraige and are now changing the game rules. To go into a relationship thinking it's one way and then realize it's something different, something that society at large isn't promoting... maybe something against everything you've ever believed... you don't just change your mind and adjust overnight.
I hear you saying that you just want her to be happy for you. I wonder if you realize what that means to her. You want her to change how she feels and what she's always thought, to be happy that you want to have emotional and sexual relationships with other people besides her. That is asking a lot.
What if she said she just wanted you to agree to be monogamous, and be happy with that? Could you adjust to being monogamous, give up your ideas of what you want and who you are for the other person?
I'm only throwing this out because I think that when you try to open an already established mongamous relationship, you have to realize how much change that is, how much work, and for some people it just won't be possible. I think not pushing and giving some time is not so much to ask.
I've heard stories about people who talk about poly and it takes years before they actually open up because it takes the mono person that long to adjust, and for the couple to work on their own relationship to get it strong to the point where poly is possible.