Naming a Business...

Hello All:

I have a question about naming a business. I use to date this guy who started a promotions company in West Virginia, but tells people that it is out of Altlanta, GA. He used my last name, which is not common. Can he do this without my approval???

I told him that I did not like that. He said that he "will not change it because other people have that name and I can not prove that he didnt use it from that", but odds are if they have the same last name as me, i am related to them. He is currently in the middle of trying to put together a music concert under this current name? He is going through major companies trying to gain sponsoorship with this name.

What can or should I do?

All help is appreciated.