howdid- it will get better- promise.
I was in your situation 15 years back. he walked away to save my marriage and try to mend his. He ended up getting divorced, re-married and now his wife has left him. He is back in touch. Hand on heart, I don't know if I feel the same. Years back I would have given my right arm for this situation- my kids are now adults and I am a lot freer than I was then.
However, in the intervening years I met someone else- he was a friend to begin with, and we talked/emailed for 2 years, but then he moved the boundaries and for me, i think it became love/soul mate- at a distance. For him though he was half-in, half out of a long distance marriage , and simply not ready either for anything else, or for me ! he did lead me on, then backed off big time when I thought he meant it. He has distanced himself, we haven't talked for 5 months bow, and I am feeling sad and miss him terribly as a friend if nothing else.
My marriage goes on in the background, but it's not great. My DH is not a communicator and I , like you, am a writer. Both the OM I have become atached with have been very articulate.
Like you, my DH knows all is not great in our marriage and we are trying to make it work.
Reason for telling you this is that I thought I'd never get over the 1st OM ( we actually knew each other from school days) but I did.
I can't advise you but part of it is about acceptance.
It is early days give yourself time.