Congratulation and welcome, Alissa.
I was an drug addict and alcoholic, and I understand your problem very well. Itīs perfectly normal to feel this way, because you are under stress while your body and brain is getting rid of the drugs. It can take a while, so donīt be alarmed if this happens from time to time.
Itīs always good to talk things over with a therapist or psychiatrist, and I believe itīs essential to come out of isolation and be involved with a good group. At least it worked for me. Whatever you choose to do, donīt take on too much - remember the treatment can be incredibly stressful - and write everything down. This way you wonīt forget. When you catch yourself reading and not seeing what you are reading, put the book down. Your brain is telling you this is too much. Surrender to it, then try again. This takes time.
Good luck!