Text Message Agreement

Pain and Suffering case was settled and my mother wanted to avoid the family getting together to discuss distribution settlement, so she sent my a text promising me to just sign document and she will give me $50K once the decree is signed and money arrived. The text messages are very explicit about the agreement. Now, I am asking her when I can stop by to pick up the check and she is not responding. I have all the text messages stored. How can I go about ensuring she does not rescind on this agreement? We are nervous that she is not going to honor her obligation. Again, the text messages are clear and succinct. Any guidance would be much appreciated, thanks