I wanted to welcome you here.  If you truly want to get clean, you will do it.
Thanks for "shedding the light" about your situation.

Since you have perhaps TBI (tramautic brain injury) could you go back to the Doctors and see what you can do for healing?
Maybe after you get clean for a while you can think about doing that.  Do you have any resources there for the PTSD? 

Every day will continue to get better if you stay clean.