How does Dr. Jeckel fight off Mr.Hyde, you asked?
Well, the simple answer is that he/you doesn't!
The Big Book of AA addresses those moments when we are unprotected from that next drink, and in those moments, it is only the condition of our spiritual lives that determines our actions. I don't know whether or not you're in AA, but this is the answer any AA oldtimer will give you. And it is not mere theory- certainly not in my own experience. I have walked away from taking a drink in situations which were tailor made for me to drink- and I wanted to take that drink, yet I did not. It is a total God deal that I didn't. I can recall one example in early sobriety when no one knew I'd stopped drinking that week and started going to AA. It was at one of my best friend's weddings, I was just 25 yrs old and all my friends were seriously partying. When the waiter came around with the champagne, I wanted it so badly I could taste it. I mean, no one there knew I had stopped and no one in AA would know if I drank, right? But I said a silent prayer asking God to please help me turn down that drink. And like that, I turned my glass over and said "no, thank you". I was shocked. But what was so cool was that at that very moment, the desire to have that drink was removed from me. And for the rest of the wedding reception,I had a blast and was not obsessed by that desire. Freaking amazing.
Anyway, there are situations like that for all of us, especially in early sobriety. That's when your relationship with your Higher Power is what matters: not your own will power!
Good luck and congrats.