I just found about my son. I'm from nj he's in Texas. His mother promised him to me and reneged on it. I have been here in Texas trying to look after him. She gave him away to a neighbor saying I rather you have him then his dad. I could not do anything. Now I have gottena DNA test he is 99.999%
Mine. His mother has 5 kids living in a 1 bedroom and also uses pills. My son ran away to my house also and had to go back cause of perturnity. This person has him I am the father and I'm afraid for his welfare.

Sent back where, to whom?
You need to go to Family Court and file for custody, with your DNA evidence. Look in the blue pages of the local phone book.
How long can you stay in Texas, and do you want to return to NJ with the boy? That could be a problem if his mother fights for part custody (or even full custody, just because she doesn't want you to have any at all). If you can afford a lawyer, get one.

A child is not property that can be "promised" or just given to someone. Have you filed for full custody in Texas courts? Even if she had turned the child over to you, you could not have legally taken him home until paternity and custody was legally established.

Before going to TX you should have retained an attorney in TX to file for custody. If you haven't done that yet, do it now. You may have to go back to NJ without your son until this is sorted in the courts.

But the fact that he is biologically yours and the fact that the mother tried to give him to someone else gives you a good chance of getting custody as long as you do it right.