You're not a failure. Alcohol is cunning and the lure to drink can be impossible to ignore in an alcoholic. You said in your first post, "...I want to learn how to become sober."
How are you learning to be sober? Are you in a recovery program? Counseling? Your relapse should have taught you something...that quitting alcohol alone doesn't always prepare us for staying sober. Work on getting a plan in place if you don't have one.
Good luck.