I’m so sorry, it’s SO hard to lose a horse you really love 
When I lost the real JB, things were very weird for a long time. He was my first horse, I had him from age 5 to 20, and while most of those years were with him on full care board, we did a lot of things together, including a lot of early morning braiding and schooling sessions for on-site shows. I had him on full care board next door when we moved to our farm, for about 5 months, and then here at home for only 6 months when I lost him. I lost him very suddenly, on the operating table where they found many feet of dead intestine due to a strangulating lipoma, so I never got to really say goodbye. The grieving after that was long and hard, made worse by Rio, who was the sole horse at the time, who called on a regular basis, and it echoed in the woods.
About 1 month later I got an OTTB mare (who I still have, 18 years later) but for an entire year, she was “not JB” to me. She was cool, and fun, but she wasn’t JB, and that’s all I could see, because that’s all I focused on. One day, I finally started seeing her for who she was, not who she wasn’t, and that made a world of difference.
It’s been 2 years today that I lost Rio, maybe even more of a heart-horse than JB was. I got him at 6 months, and he was 21 when I had to say goodbye after a chronic lameness he’d managed well with for about 10 years, suddenly became unmanageable. I had months and months realizing his time was coming up fast, so a lot of grieving was done before that day. But in days and weeks after, every First - not fixing his meal, not cleaning his stall, not having 3 stalls filled, not seeing him peek from out behind the barn - took me down a little notch, and kept me from enjoying the 3 horses who were still here.
Eventually that faded.
The points of all that are:
1 - take the time it takes, do the things it takes, for you to grieve, not what anyone else says should be. BUT, the longer and the more you wish for what can never be again, the more stuck you’ll stay. This goes for everything, not just horses.
2 - you have to figure out why you are/were into horses to begin with. If you only got into horses because you met that one, and had no real interest before, maybe this is it for you and horses. But I’m guessing that’s not the case, so at some point, just think about what horses do for you, what feelings they bring, what experiences they allow you to have. There is another horse who can, and will, do those things for you, either in part (because face it, we don’t jive with every single horse), or in totality.
3 - Realize that a next horse is never a replacement. Yes, it’s a body replacement (and expenses!), but the relationsip is never replaced. It’s going to be unique, and quirky, and if one of your things in #2 is that you want to become a better horseman, then everything about the next horse will improve something, even if that one isn’t the next Forever Horse.
