We seem to have a similar story. My WAS told me he had lost the lack of intimacy and sex for me basically month after your H told you he wanted a divorce. The difference in my story is that it was my H who was distant and I who would like to engage more. I knew we had issues but I had hoped we could work it through.
Like you I am finding detachment hard. My H is living downstairs and we have two Ds. Hang in there..
Me: 39 yrs H:45 yrs M:14 years T:18 years D:10 D:6 BD: 13/04/15 S: in progress