need info on Texas

I moved to Colorado from Texas 3.5 years ago in order to be near my mom, who was ill. The kids and I had not heard from my ex for 7 years. No cards, no nothing. Even though we had been advised not to give him our physical address by a crisis counselor, we did provide him with a post office address at all times, even during the move. He finally wrote on 12/97 to our address in Colorado and wrote several letters to the kids and I till 1/99, when he wrote the last one, which was signed "suicidally yours". Now, he is modifying the child support order, which is O.K. with me. I would sign the paperwork, but it says that I must notify him of not only our mailing address, but our physical one, too. And my work address. This man has only supervised visitation that he has never used. The kids and I are afraid to give him our physical address and I work in an office where the work force is spread out all over the city and I am alone most of the time. With the last letter he wrote, I am afraid to list this information. Do I have to?
Please, someone who knows Texas Law, please let me know what I can do. I cannot afford to get an attorney in Texas for this.
Thanks.