Helen, I'm so sorry to hear about your loss. We had to put one of our dogs down just before we went up to Scotland in the summer to see my Mum and it was very wierd. Even now that a few weeks have gone by when I go to give Ralph a biscuit I still automatically pick up 2 biscuits and my heart aches as I have to put the other biscuit away. Its hard, ut it does get easier. Ralph is getting used to not having his bed mate, but has lost some of his confidence which in a way has made him more loyal.
It gets easier to live with, but its hard - a big hug to you.