Can long term damage to personality be reversed?

Hi, We got married really quickly, within a year of meeting. My wife has been struggling with a metamphetamine problem on and off for about 15 years prior to us meeting. I have not been able to help her stop completely, and it has been the cause of much conflict and unhappiness within our marriage. Now she is being treated and things look positive for the first time in a long time. My concern is the effect of metamphetamine on the personality is very destructive. I have researched many papers relating to the loss of sympathy and less compassion exhibited by users over time. This seems so with my wife as she becomes a different person completely when she has taken anything. She becomes a cold and careless person who does things out of selfishness or spite. I know she is normally a caring and kind person, but more and more I am seeing these negative traits show through when she is sober and not only when she has unduced the substance. Will these negative traits remain after she has beaten her addiction or will she return to herself over time?