you are not abandoning him......he was an alcoholic BEFORE you and remains the same. your "influence" in his life did not CAUSE any change - being together didn't fix it, living together didn't fix it, and leaving doesn't fix it. he IS as he WAS.
you are very wise to end things. his fealty remains to alcohol, with no exception. until HE makes the decision to truly accept he has a problem and then dedicate his LIFE to resolving that problem, what you see is what you get.