This is often in addiction seen as the great offender which destroys life emotionally ,  This is because with addiction resentment invites using which then means one is mentally and physically ill.  I see resentment as a spiritual disease whether attached to addiction or not.  I have seen this process in my own family which depletes ones spirit and leaves a bitter and twisted soul.  Who eventually has the potential to live out a life script of early death through stress and being alone because they have pushed others away.  The substance just makes this process much quicker and obvious.  Therefore , resentment is a kind of killer of the heart as it closes it to love, compassion and warmth.  It leaves the heart exposed to selfish pride, jealousy, envy, selfishness, dishonesty, greed and hate etc etc.  We cannot flourish emotionally and evolve as human beings in a healthy way with resentment being in the way.  Through life and as children we have possibly collected resentment because of life, situations and love with our attachments “in some way not being fair”.  This could be because a sibling was favoured, or we did not have as much as other kids and were considered poor.  We could have suffered abuse and therefore our relationships are fragile to paranoia and not believing in others kindness and love.  Or neglect and we resent those who do well and blame the system for our lack of life vitality.  Others are perhaps having bullying in our background and then having issues with any authority ,thus, dis-missing any advice which could even be of benefit. Even with backgrounds that would not be considered particularly difficult a child can collect resentment.  Human beings seem predisposed to collect resentment through life not going the way they want.  Theorist Piaget wrote about “egocentrism”  in development and the age of 7 when one realises that life is not all about them.  If this process is successful  this lesson is learned and helps with our self absorbed neediness.  However, the process no matter how its experienced does not go without pain.  As we discover that we are not central to the universe which can be frightening, painful and cause dis heartening.  Perhaps in addiction its a way of finding a centre to go back to in gaining the importance and feeding ourselves to soften the pain.  There is a conflict and discrepancy between being selfish as in early life we had to  survive in attachment thus, could be considered self preservation and  needy, ego centric drives that feed the loss of importance.  If the loss is so painful is it any wonder that children carry resentment that can have emotional consequences.  The list of what effects resentment can have is endless and powerful in how it makes people behave and see the world with often disregarding what can even be beneficial.  The sad thing is often situations that created pain in the past can then present themselves in adulthood as resentment.  The actions are vast were this can be see from dishonesty, self seeking, and inconsiderate.  However, often under all of this there is a frightened person who really wants to be free of all this contamination of the soul yet does not know how to.  This is where Step 4 on personal inventory is really important as we can look at the self.  The objective is to get to the causes and conditions and fears..