For me it was a horse named Ol Big Deal. Heck, I cannot even type his name without tearing up and it's been 6 years next month. We had 25 years together. When he died, a part of me died with him. I know EXACTLY where you are coming from.
I hear you loud and clear....Jan 21, 2001 for me losing my 13 year old wolf...not a day goes by that I do not miss him or a night that I do not feel him in his spot on the floor beside me.