Congratulations on your month of sobriety, Hopeless. That is very impressive, especially with all you have going on in your head and heart.
Now is the time to shift your focus away from your ex and on to the only person you are guaranteed to be with for the rest of your life: You. You can try to pick apart what happened all you like, but it's just pulling your energy away from your own recovery. I'm not an alcoholic, but I have a long history of relationship addiction -- believing I was not worthy unless I had a significant other to validate me, unable to exist happily in my own skin, and always wondering what I could do or say to make another person give me what I refused to give myself: love, respect, kindness, validation.
Through recovery I learned that I was never going to have a healthy relationship with anyone else until I built a healthy one with myself.
I'm very glad you found SR, though sorry for the reason you came looking. Please keep reading, there is a wealth of experience, strength, and hope on these boards. Good luck.