I can relate to your problems. I live with my husband of 40 years who is presently a dry drunk, my 35 year old son, who has been unemployed for about the last three years, and my 19 year old grandson, whose mother (my daughter) suffered from schrezephania and completed suicide in 1995). I am getting ready to dissolve my marriage and move out.
My son and I get along great. I'm trying to help him set up our own small business. My grandson is the one that reminds me of your son's emotional reaction. I don't think he is drinking or drugging, but I'm afraid he might have a personality disorder, like his mother. A person never knows how he is going to respond to anything. I suffered a massive stroke in DEC 2009, and almost died, and now have immobility problems.
I have had to call the police a couple of times to help me calm my grandson down. In my state a person has to go to the constable and draw up paperwork which is given to that person, and then they have 30 days to finally move out. I understand 100% about your feelings about using 'touch love' with your son. After all, us, mothers believe in unconditional love towards our children. However, there is always that ultimate decision. Most cities and states have a family crisis center you can call for assistance. I realize that as codependents, we have been taught to keep family secrets, but you need to accept this problem with your son is bigger than what you can handle all by yourself.
Is it possible to catch him in a good mood in order to talk with him? He needs to understand you do have house rules and in order to 'freeboard' from you, he will abide by them. Set up your boundaries with him, and if he oversteps them, then make him realize you will no longer be his pounching bag. Us,codependents, can become used to being pounching bags either physically or by verbal abuse. In order to calm your relationship down with your son, you might want to be prepared to move out temporarily, and give him some time to come to the realization of what his actions are costing him. He needs to know that for every action there is a reaction.
Starting Al-Non is a good starting point, but you need to work the program in order to see results!