As long as Op and her mother (and any other family members) keep enabling him to be the irresponsible drunk that he is by not doing anything out of fear of being without, then he will NEVER change and lets hope if he ever has a drunk driving accident that it only involves himself.
You people really need to stop being the enablers that you are and kick his ass out of your lives and not allow him back until he is sober for at least a year and attending either personal therapy or AA.
Y'all should be in Al-anon to help you with your enabling tendencies.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion