Upon death, title to the decedent’s property passes immediately to the beneficiaries under the decedent’s will or to the heirs
-at-law if the decedent died without a will. Based on the information you have provided, no will (or a notarized paper) has been produced.
Accordingly, the former caretaker/girlfriend is entitled to nothing, because she is of no relation and has produced no will giving anything to her. You are a relation, by virtue of your aunt being his mother (by adoption), so your claim is greater than the caretaker, assuming there is no other relatives closer in relation to him than you (such as children, grandparents or siblings). I have provided a web address below to the Texas laws governing heirship
Nevertheless, there must be an actual transfer of ownership of the property by proving the will in court or, if there is no will, by having a court determine who are the decedent’s heirs and what is the property to be distributed. Until then, no one has a claim that is likely to be recognized by a third party.
Therefore, to protect your rights and receive whatever interest in the property you are entitled to receive, you would need to initiate a succession or probate
of the deceased's estate
. You can contact a local probate attorney for assistance, or the legal aid office serving your community.