Scott,
It is natural to seek happiness, but it shouldn’t come at the cost of hurting others, such as your wife. I think what is most important is that if you haven’t already spoken with your wife, you should do that. Marriages has its ups and it’s downs, seek marriage counseling if you have too. Maybe the happiness you seek is right in front of your face but you just cant see it yet. You may have married for security, but you need to ask why did your wife marry you?
Unless this other lady you are seeing on the side single w/no kids, then you have lots more to lose, while she doesn’t really lose anything. You are not even sure if she feels the same about you as well.
If you do want out of your marriage, thats one thing. However, you should do these things for yourself, and not for other people.
@Linecrosser: Your laugh reminds me of the Joker.
Sincerely,
The Dark Knight