I don’t know how you allowed “someone”, to have your Social Security #. They can take your identity away from you. Open credit cards, obtain drivers lic., passport, birth certificate, etc. etc. and just about everything that you would require to have ID for.
Having your S/S is not against the law. If criminal activity is used with your S/S, then it is a crime and not legal.
Example if I have your S/S, all I have to do is call the Social Security Administration and tell them I lost my Social Security card and give them your #. They will send me a new card.
Obvious you reside in the United States, being you have a Social Security #. Suggest you call or visit the S/S office nearest to where you live and file a report if your # has been stolen.
And away goes your idenity.
Minddoctor, France