While you don't give all the details of this negotiation (nor should you in an online forum), from what you've said, your attorney sounds like perhaps a bad negotiator who has made some tactical errors or blunders in his negotiating posture. However, even if some of these positions were premised on errors of understanding of the law, usually they don't rise to the level of malpractice or ethical violations unless they were grossly negligent.
In this instance, the law regarding equitable distribution is fairly clear (you've correctly stated them and your attorney undoubtedly knows them too) and it's not clear whether opposing counsel is a better negotiator or your options for a better deal are limited and you and your attorney are "boxed in".
Negotiation and settlement are substitutes for litigation, in which a judge and or jury will decide between two opposing positions. Sometimes there are "winners" and "losers", but it's not the attorney's fault, he tried to do his best with the facts and law he was stuck with. That's why negligence/malpractice are usually clear-cut violations or attorneys "dropping the ball", not preparing the case at all, missing filing deadlines or court dates or simply refusing to do any work or communicate with clients after he's received fees from them.
Unfortunately, the summary of facts presented doesn't sound like malpractice/ethical violations to me. It just sounds like perhaps at most tactical blunders dealing with limited negotiating options. That's not actionable by you against your attorney.
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I agree with Mr. Lebowitz, and would like to add that, in Texas, unless you were married less than a year, and your spouse has the same earning power as you have, the court will usually begin "just and right division" at 60/40 for the spouse with less assets. This is because Texas is a community property state without alimony. Considerations in discerning division include length of marriage, educational levels of respective spouses, earning power of respective spouses, and contributions made ( non-monetary) of the spouse to your business. So the offer from other attorney may be reasonable, even if you don't like it.
Discuss clearly all the issues you have with your attorney. If you are truly dissatisfied with the attorney representing you, change attorneys. But you should meet with your attorney about the concerns you have listed here, to clear communication issues.
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In court cases, one side always "wins" and the other "loses." Of course, its always more complex than that but it still serves to illustrate a point about grievances. Simply achieving a bad result from litigation does not expose an attorney to ethical violations and a grievance, otherwise ALL attorneys would have a long history with the grievance board. Sometimes the underlying facts of the case drive the bad result, not necessarily the attorney's actions. A grievance is appropriate only in limited circumstances where an attorney has committed malpractice (done something no reasonable attorney would have done) or done some unethical (like a conflict of interest, having an inappropriate relationship with a client, or stealing client money).
I think the best thing is for you to have an honest, polite, and open conversation with your current attorney. Explore options for how this bad result might be repaired.