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Your legally married spouse may only file as head of household if you did not live in the same household with her for the last six months of the year. This also presumes she is claiming dependents and provided more then one-half of the support to provide the household.
Whether your spouse legitimately claimed HOH status or not, your only option is to file as married filing separate unless she would be willing to amend her return to file jointly with you. Also, if she itemized then you must also itemize (i.e. you cannot claim the standard deduction if she itemizes). Alternatively, if she claimed the standard deduction then you must as well.
Because it is impossible for me to identify and consider ALL the relevant facts, this advice is not intended or written to be used for the purpose of avoiding penalties, and cannot be used for that purpose.