Estate Law Questions? Ask an Estate Lawyer.
If your Mother left a Will, and you are the named executor and sole beneficiary, then you will need to open Probate to have the title to the property transfered to you. Your sister does not have a claim to the property if it was not left to her in the Will; but it doesn't stop her from contesting the Will if she chooses too. This would require a showing that the Will is invalid. If both your Parents are named on the Note for the property when your Father died the entire property was owned by your Mother, she then devised it to you.
At this point you do not need anything from your Sister, you should seek a Probate attorney in the county where your Mother resided at the time of her death, or where the property is located. The attorney can help you Probate the Estate and get the property sold, you will not be able to sell the property until the property is properly transfered through the Texas Probate process.
I didn't realize you went through probate. If that is the case then the title should have been transfered to the person the property was devised in the Will, once Probate was closed. The Estate owns the property during Probate and when the Estate is distributed it is transfered to the beneficiaries name. Once that is done the person owns the property, and can dispose of it any way they wish. The deed should now have your name on it, not your deceased parents.
You stated that the property was given to you in the Will, and no one else. If this is the case then no one else has a claim to the property.