How can my fiance obtain a copy of the Special Warranty Deed he signed in court if it wasn't filed?

My fiance ex-wife was awarded the house and he signed a Special Warranty Deed in court but never received a copy. It is also noted in the divorce decree that he signed a special warranty deed. We went to the Dallas County records department to obtain a copy and was informed that there wasn't a special warranty deed filed, only the original deed of trust. She is remarried, they are constantly late and behind on their payments, he is receiving calls from the mortgage company. He said there was a part of the special warranty deed saying that if she fall behind he could sale the house (not in those exact words). He have asked her to refinance to remove his name from the loan, she refuse to do so. He called the mortgage company and they sent him some "Assumption" forms to mail to her. We have done that and still nothing. We are currently engaged and eventually we will be in the market to purchase new home ourselves. He keep asking her to refinance or fill out the assumptions forms.