Kixster I am so sorry his mother unloaded on you like that. Of course everything she said can be chalked up to the incredible denial that often surrounds families living with addiction. These are deeper hurts than you can heal. Please resist the urge to take any of it--what his mother says and what he says--personally.
Sadly, it seems that he still has plenty of enablers in his pocket. Please don't let his unwillingness to change keep you stuck in such an unhappy situation.