Unfortunately, I have no additional information to give you regarding your ancestor. If you know where your ancestor lived after the war (assuming that he survived), then I suggest that you search for a state pension application. Pension applications often have more information than a service record. If you would like additional information on the 28th Texas please see my book: PECULIAR HONOR: A HISTORY OF THE 28TH TEXAS CAVALRY, 1862-1865. University of Arkansas Press, 1998. If you want to read a brief history of the 28th please look at the following website:
www.tarlton.edu/~kjones/TXCavHist.html
Scroll down when you get to that site and you will see a history of the 28th. Just so you are aware, Mr. Bray accidentally attached officers and company information relating to the 13th Texas Cavalry rather than the 28th Texas in his response to you.