Keeping the most important things in your life a secret is psychologically harmful. So is believing that your feelings are wrong. That's why being forced to be in the closet is so bad for people, whether it's about being gay, being trans, being poly, whatever. From reading your other post, I would venture to say that it DID mean a lot to you, and that's why it's affected you so deeply. The question is, is the freedom to openly love more than one person something you need in order to be happy?
I would suggest talking to your wife and working towards the point where it's very clear about what you both want out of the future. If you're going to do monogamy, then focus in and heal your connection. If you're going to do poly, then do the exact same thing, and once you're in a better place, then you can think about dating others but without the secrecy and the feeling like your feelings are wrong. Lots of good resources for how to start with this at www.morethantwo.com