You must file a "Notice of Claim" against the estate with the probate court where your fiancee's estate is pending as soon as possible. There is a limited time frame in which to file a claim, so don't wait around. You may want to contact the court and ask if they have a claim form in the office or online. Make sure you can document every cent contained in your claim, because the court will require authentication.
Below are a few statutes that detail the claims process.
Tex. Prob. Code § 294 (2007) titled "Notice by Representative of Appointment" mandates the following:
(a) GIVING OF NOTICE REQUIRED. Within one month after receiving letters, personal representatives of estates shall send to the comptroller of public accounts by certified or registered mail if the decedent remitted or should have remitted taxes administered by the comptroller of public accounts and publish in some newspaper, printed in the county where the letters were issued, if there be one, a notice requiring all persons having claims against the estate being administered to present the same within the time prescribed by law. The notice shall include the date of issuance of letters held by the representative, the address to which claims may be presented, and an instruction of the representative's choice that claims be addressed in care of the representative, in care of the representative's attorney, or in care of "Representative, Estate of " (naming the estate).
(d) PERMISSIVE NOTICE TO UNSECURED CREDITORS. At any time before an estate administration is closed, the personal representative may give notice by certified or registered mail, with return receipt requested, to an unsecured creditor having a claim for money against the estate expressly stating that the creditor must present a claim within four months after the date of the receipt of the notice or the claim is barred, if the claim is not barred by the general statutes of limitation.
§ 298 titled "Claims Against Estates of Decedents" requires the follwing from a creditor:
(a) TIME FOR PRESENTATION OF CLAIMS. A claim may be presented to the personal representative at any time before the estate is closed if suit on the claim has not been barred by the general statutes of limitation. If a claim of an unsecured creditor for money is not presented within four months after the date of receipt of the notice permitted by Section 294(d), the claim is barred.
(b) CLAIMS BARRED BY LIMITATION NOT TO BE ALLOWED OR APPROVED. No claims for money against a decedent, or against the estate of the decedent, on which a suit is barred under Subsection (a) of this section, Section 313, or Section 317(a) or by a general statute of limitation applicable thereto shall be allowed by a personal representative. If allowed by the representative and the court is satisfied that the claim is barred or that limitation has run, the claim shall be disapproved.