This is a really great thread--thanks for asking the questions, TFM, and thanks to all who have posted here.
For me, the reasons I didn't leave fall into a few different parts. It was a total of about 7 years from the time I knew he was drinking alcoholically to the time I asked him to move out (we had divorced about 6 months prior to his moving out; he was living in the upper unit of my house). During the first 4 years, I believed that he was going to AA meetings and had stopped drinking, b/c that is what I was seeing. I didn't understand the other changes that come w/recovery that should have been showing up and were NOT. I did nothing for my own recovery during this time, fooling myself that if only HE got sober, everything else would resolve itself.
After 4 years, I learned that he'd never stopped drinking at all or attended any AA meetings, was only pretending, and I finally came here and started to do Alanon, starting to work my own recovery. He began to actually go to AA meetings and claimed he was sober, but this turned out not to be true. I continued to not leave during this time b/c I simply couldn't believe this was how it was going to be. I absolutely could not accept that my "perfect" man was not going to see the error of his ways and all he stood to lose and come around! How could this happen? How could he not get it? I felt sure he'd eventually get sober.
And eventually, during the last 2 years, it was fear that kept me in the marriage. I really didn't have any hope any more that he was going to quit drinking or lying. I was just too afraid to be on my own--financial fear, fears about keeping up the house and land, handling maintenance, fear of having no one b/c I had allowed my world to grow so small I really had no friends any more. Fear about pretty much anything you can imagine.
And you know what else kept me there, maybe more than anything else? Memories. Memories of all the things he and I had done together or that he had done/made/built. We laid a pine floor in what is now my big bedroom. We drywalled the bathroom and he laid a lovely tile floor in there. He put in nice blinds in most rooms. We had years and years of snow shoveled or blown, grass mowed, gardens and flowers planted, weeds killed. We had dogs almost the entire time we were together and put in miles and miles walking the various dog combinations over the years. We'd worked at some of the same jobs in times past.
I think it was that, more than any other single thing, that kept me there. If you have memories w/someone, and they are the only other person that shares those memories, it feels like the memories cease to exist if you're the only one who knows about them now.
As far as how to live after the marriage or other relationship ends? For me, it's been similar to what others have said. I've learned how to do some of the maintenance around the place myself, and I've found some help for the things I can't do, like cleaning gutters on my 2-story house. This A) gets the work done and B) gives me confidence that I CAN handle those things. I've made an effort to get out among people, learn some new stuff, make some new friends. It's slow going, but thank heavens for SR and Alanon, I've learned that it's OK to take my time making friends and finding activities to do and groups to be in. I am reading a lot, exploring, learning, expanding, in so many areas, and I can feel changes taking place. Every time I feel I've moved ahead a little bit, it fuels me to continue working and continue moving ahead.
That first summer of 2013, when I had believed him about his sobriety and recovery and then found his liquor stash in July, I was crushed. I couldn't imagine how I would live. I felt angry, betrayed, frightened, confused, sad. It was an awful time. I would have never believed, 3 years ago, that I could feel as good as I do (most of the time) now, that I could have made the changes I've made, and that I would be looking forward to continued growth and new experiences, feeling (most of the time) that I'm going to be OK even if I don't know exactly what the future holds.