Than you for the time and trouble taken to post this soldier's thoughts and feelings. It's really compelling.
There certainly was a Confederate command named 5th Alabama Cavalry Regiment, Colonel Josiah Patterson. Of 126 names on record for Company "B", I'm not able to identify twenty-eight. In 1860 twenty-seven lived in Marion County, twenty-six in Fayette County, sixteen in Tuscaloosa County, eleven each in Lawrence and Winston Counties, five in Walker County and two in Franklin County. This company organized at Union Springs, Morgan County AL, Sept. 10, 1862.
In late October of 1864, a reorganization of Roddey's command brought about consolidation of the 5th and 10th Alabama Cavalry Regiments. That may be what you have seen mentioned. Let me know if you have other questions.