@thefoolsjourneyman
I think this is the main crux of it. I don't doubt that people spend years and years sleeping in different rooms or not having any physical contact. It's quite common.
He knows that going away with her will hurt you, and that staying with her is hurting her. But you're right, he is a coward who is scared of hurting anyone and you're right, he will end up hurting you all.
I would say, get out now. Even if he was a friend. I have walked in your shoes and it didnt end well for anyone. They are still together, still unhappy, he is still a coward and still can't make a decision, this is years later.
People do sometimes spend their lives in miserable marriages, just existing, the fear or change is too much for them, this goes for both men and women.
If you have the courage not to be that type of person then you ultimately you will be happier.
Losing someone you love is hard, but ultimately this will destroy your sense of self