Hang in there. Sure my situation is very different to yours but I can relate to the emotional rollercoaster you describe. I don't know what else to say other than just hang in there and stay away from that first drink. I relate to the fact of not drinking not really being the issue per se, but instead feeling flat about yourself and life in general.
I had 8 days solid over xmas through to NYE where I would describe my mood as 'dark'. I felt how you describe very much and my mind was constantly racing back and forth wondering wtf it's all about. Keep the faith that you will come through the otherside and the reward from it will be peace, serenity and strength. It was for me anyway.
Keep The Faith xxx