Use of our last name by ex

My husband's ex is using our last name, even though she is married to one man and has been living with another for about 3 years now. Is that legal? We live in Texas. Somehow, it doesn't esem on the up and up. She says it is for the kids. It only confuses everyone where the children go to school...they live with us, but have visitation. People in the business we are all in confuse her with me - until they know us. She has a bad history with hot checks,,,, and drugs.

My response:

There's nothing illegal about her using any name she wants to use.

Would you not agree that there are families out there who have the same last names, and who are not even related in any fashion ?

I'll bet you even know different families with the same last name.

Sorry - - there's nothing you can do about it.

IAAL