Hi Stewy. Rather than a "reset" button, how about just a "pause" button. Just for today, concentrate on not having that drink. You know that it will just lead to chaos. So not worth it!
I feel both you ,and your ex's pov. Is she having a crappy day? Sounds like August is along time ago to bring something up that has been resolved. I second the question in how old your daughter is. My son is 9, and I know that there are things he shares with me rather than my ex. How is your daughter with you now? Can you perhaps suggest to your ex to try some sort of counseling? The most important voice to me that should be heard is your daughters, and sometimes someone who is not emotionally vested in the relationship can really be beneficial. One thing I try to do with my ex is write everything down that I want to say to him. We really bring the worst out in each other and it doesn't take long to get into a pissing war over something small.
With your current gf, hopefully you will get a chance to sit and talk with her this weekend. See how she is feeling. Day to day stressors really take a toll on a relationship. Hang in there!!!