Many people like the "let the judge decide for us" idea because the judge must rule based on the guidelines of the law. In most cases (in a no fault state which I think you are in?) it will result in a fairly even split. If your W feels what you are offering is not all she is entitled to it's not surprising she doesn't want to work with you.
If you had an agreement in place via mediation why wasn't it filed when the agreement was reached?
