Separated from partner who is not letting me get personal property, what are my rights to get property back under TX state law

You probably need to file a lawsuit immediately and try to get an emergency ex-parte order restraining her from disposing of your property. A judge may or may not grant one, but obviously time is of the essence. Your next problem will be proving what property is yours. She may try to say you abandoned the property and thus claim it is hers.
If money for an attorney is an issue, you could sue in small claims court which has jurisdiction up to $10,000 but cannot order her to return anything. In small claims you have an informal procedure, you tell your side of the story (and she hers) to the judge who makes a decision and renders a money judgment from $0 to $10,000. The judgment can be appealed by either side.