CDK, I emailed your post to two of my friends who have been helping me get through this latest "episode" with my XABF. It is amazing how your words could have easily been mine.
He told me I was the last woman he would ever be with. We would grow old together. We would travel together. Every conversation ended with "love and miss you." He would finish drinking forever within three weeks. We were going to plan our next vacation when we got back from the one were on. He had a list of about a dozen "get my affairs in order" things to do in August. He was talking about a complete turnaround.
What he did instead ... went to Key West with friends the next weekend, binged days and nights away, watched two women have sex in the back of his SUV on the way back, quit calling me altogether, and went back to a bar trash XGF.
He walked away from it all, and the only thing I can say is that he's demented from the drink. I agree - they are sociopaths. It's like a demon is possessing them. Or maybe it's a slow suicide. Or self-loathing. Or all of it wrapped up in one.