I'm approaching the first antiversary too. The upside being that this is the last of the "firsts". I made it through this year and I'm in a far better place emotionally and mentally than I was 12 months ago.
Had DD not happened I might still be in the dark about my husbands betrayals, I might still be exposing myself to his STDs, I might still be in a desperately unhappy marriage and wondering why.
I don't see those last weeks and months we spent together as last days of our marriage. For me the last days were before he detached from me and his family, before he abandoned me and my girls emotionally and physically, before before he got on that slippery slope, before he walked to the edge of it, before he looked over it. All WELL before he slid right down it.
Be gentle with yourself - this has been a hard time for me. Not in a wistful way but in a dripping with regret way.
This too shall pass.