Can my wife fire me as CEO?

It depends on how your company is structured. Does your wife have an equity ownership interest, or is the remaining 20% owned by a third party? If you and not your wife holds equity, then the company will remain yours. A valuation of your company will be necessary to determine its fair market value, and your proportionate share of its net worth. Your wife will be entitled to share in your interest. Depending on various factors, she might or might not be entitled to 50% of your interest. Once a dollar value is established, you could buy your wife out of her share. This can be accomplished by offsetting the value of other marital assets or a cash payment.

If your wife also holds an equity interest, a determination would have to be made as to whether you both want to remain in the company, or whether one of you will buy the other out, or place your combined interests for sale to a third party.