It is the law in every state that a child born to a married woman is presumed to be a child of the marriage. Some states are more logical than others and make this presumption contingent on the child being conceived
during the time of the marriage and/or also require that the mother and her husband be cohabitating at the time of conception. However, other states only care that the mother and her husband were married at the time of birth. Not entirely sure about Texas.
In any event, if the woman's husband believes he is not the biological father of the child, he can dispute paternity and seek to prove or disprove paternity with a DNA test. Such an action typically needs to be taken within a very
short time after the child is born (four years is the longest time I'm aware of and, again, I'm not sure about Texas law). If your husband failed to dispute paternity within the appropriate time, then, as far as the law is concerned, the child is his, regardless of DNA.
I'm not sure what "contact Florida" means. When did the mother and child move from Florida to Texas? Also, you wrote that you and your husband don't reside in either Florida or Texas. Where do you live now, and when did your husband leave Texas?