He is basically following well worn addiction patterns.
I'm not THAT bad
"Minimization and downplaying of the problems connected with addiction fill in the gaps and take up the slack left by the failure of psychotic denial to adjust reality completely to the requirements of the addiction. The addict admits that difficulties exist - but he stoutly maintains, frequently in the face of an astonishing and rapidly accumulating mountain of evidence to the contrary, that they are not really as bad as others make them out to be".
You're not so pure yourself
"Following the adage that "the best defense is a good offense" the addict seeks to turn the tables and distract attention from himself by "attacking the attacker," i.e. the individual who attempts to point out to him the reality of his addictive behavior. Under the spur of necessity to defend their addiction as they are, most addicts possess a keen eye and a sharp tongue for the shortcomings and faults of others - even as they deny or are indifferent to those of themselves. Thus the addict is often almost demonically astute at exploiting the vulnerabilities and Achilles Heels of those who, wittingly or unwittingly, threaten the continuance of his addiction".
Excuses Alcoholics Make