If she already closed the accounts, then, obviously she can do it. The bank(s) must have recognized her as having some authority to act for the corporation. However, if she is a corporate officer, then it sounds like she violated her duties to the corporation (called fiduciary duties) which require that she act in the best interests of the corporation and not put her personal interest ahead of the corporations' interest. The remedy is for you, acting on behalf of the corporation, to hire a lawyer and sue her for violating those duties and ask the judge for a Temporary Injunction restoring the corporation assets to their previous status so that the business can continue. Just because the wife owns 51% of the stock does not mean that she can violate her duties to the corporation.
I also suggest you consult a divorce attorney since you mention that as part of your wife's motivation.
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