Nola, yes, it is hard. Very.
I too, remember almost going through "withdrawals" when my soon to be ex AH left. In fact, I felt the pain even before he moved out, and we had been sleeping in separate rooms, but his moving out date had been set.
I told my Alanon sponsor and she agreed that as painful and abusive my marriage was, that I was grieving the loss of the marriage, of my partner, my lover (my first love, in fact), my bed-mate. LOL - she even bought me a large stuffed Teddy Bear to sleep with. (Sigh...RIP Sponsor - I miss her.)
Hang in there, hug a pillow at night (or a Teddy Bear).
Also, another thing I was told, when I started to "miss" him, and started to think of the "Good Times" (and we did have some) was to say to myself:
"Remember the Craziness".
And I did. Many times. This thought saved me. And the longing for him lessened.
Hugs to ya'