I lost a horse about 20 years ago and he was THE horse....just ask me I'll tell ya!
You feel like there is a piece missing because there is a piece missing. Deal with your grief on your own time, every one is different. And it's ALL OK!!!! ((hugs))
I still get misty eyed when thinking of Kip (aka the bestest horsey in the whole great wide world) and it's OK!!!
(BTW- Kip was only 28years young when he passed, age doesn't matter...it all hurts.)
(((SUPER HUGS))) we're here for you and my best advice is to sleep when you can...this includes afternoon cat naps...sleep deprivation is hard on your body and mind, and try to carry on without her. It will be a rough road ahead of you as loss and grief both suck big eggs...but you will come to the end of that road and you'll know when you're ready to get another baby to love.
Until that time, I have an unlimited supply of internet tissues!!!! Hang in there!!!