No defense against the first drink. It happens so easily. I had four months, sober but miserable. My friend offered me a puff, ... yeah thanks, felt better, felt a drink would be nice, and that led to a one year relapse that almost finished me off. Gotta ask myself, where were all the thoughts of why I shouldn't drink? What happened to my memory. Why didn't it occur to me to "play the tape through". The sane thoughts that should have saved me were strangely absent. They did not come to mind. Instead I thought I would just have a good time.
I never admired those folks that could have one or two by the way. I thought there was something wrong with them.
Don't be ashamed my friend. If you are like me you attempted the impossible. This is just a stepping stone on the path to recovery. It may take one or two more stepping stones until you find what works. Keep trying, be open minded.