There is no such system or law to give a single status certificate in Tamilnadu.
In fact one can get a certificate in Delhi or Punjab State in a format prepared by himself/herself and get it attested by appropriate department/official.
Single status affidavit India format Certificates is the act of witnessing an individual on its own status, certificate by authorized person / persons / Departments / Attestation powers that be with their official seal and signature. This attestation as well confirms that, the particular Single status certificate has been issued by that department and Seal and signature on that certifying Single status certificate is genuine.
First of all your marriage with a Portuguese girl cannot be registered under Hindu marriage act though the marriage might have been solemnised as per Hindu religious rites. It can be registered under The Special Marriages Act only and for that lot of formalities are to be observed.
You have stated that you parted ways mutually then what about the so called marriage solemnised between you both?
A single status affidavit is a sworn statement that you are eligible to marry which is also known as the “Certificate of No Record”
Single status affidavit India format Certificates is the act of witnessing a on its own status certificate by authorized person / persons
You can get unmarried certificate by filling an application form, Attestation required for getting the Married in Foreign Countries. You may refer the above paragraph for the details.