Not able to agree to any of the above views.
First of all name of spouce is not there in service book. This name is in the nominations and medical benefit papers.
You cannot exclude her name from nomination unless there is a divorce or judicial seperation. Even if you make nomination in gavour of anyone the same shall be invalid even if erroneously accepted by the deptt.
Further in case you drop her name from CGHS card this amounts to non-maintenace and you can be compelled to foot her entire medical bills from your pocket and depriving yourself of the rembursement.