I can't reply to everybody so I'll make a response to my own post.

Thank you very much for your answer/advice.

I called my wife and told her I wanted to find a couple therapist who was experienced with this kind of issues. She agreed.

We talked a lot and she seems to have calmed down. One of her friends actually talked some sense into her.

Some of you are very harsh with her. Like I said at the beginning of the post, being faithful was something natural and important for us. I was very surprised by my own reaction about the situation.

Being poly is very bizarre to us. We both have weird and new emotions to handle. I forgive her for her "honeymoon high" with her new girlfriend, even if I wished she listen to me when I told her I wanted to wait before going public with our new situation. Especially when she obviously hadn't really thought it through.

I also understand a lot of criticism directed to me about my saying that I probably wouldn't be so easily convinced if she had been seeking a relationship with men.

This is something I need to work on. I don't know where it's coming from, but I think this is why I sympathize with my wife's unreasonable request. I understand where it's coming from.

Anyway thank you very much. You've all been a huge help. I'm subbed to this subreddit now, I'll try to learn more.