I think those bitterness feelings are not only understandable, but healthy. They HAVE to come out, and as long as you're keeping your venting to a close circle of friends and family, I think you're fine. DO treat every one of those conversations as if it's going to get back to your wife, however, and let people know "I don't want a divorce," and "I love her very much" (assuming those things are true), "but I need to protect myself," etc.
Sorry, I'm not that familiar with your sitch, but I just wanted to offer you some encouragement, since you give others so much of yours!
