What kind of feelings does a person have when they are going thru a 28 day rehab facility?

My fiance is currently in treatment for 28 days for her addiction to narcotic pain killers(opiates). This is near the end of week two of treatment. The first 5 days she was in detox with Suboxone. What does a person in her situation go thru mentally with her feelings and thoughs and all during this period?

: http://alcoholdrugstreatment.info/what-kind-of-feelings-does-a-person-have-when-they-are-going-thru-a-28-day-rehab-facility