I'm so sorry for your loss. :( As others have said, everyone grieves differently and only you can decide how to best cope with your loss, but I will tell you what I did. I lost my horse in the same way, to a twisted gut. I had her for 22 years and it was so hard. She, too, suffered a long time while waiting for the vet. Anyway, I bought Stella a month later. Not as a replacement, but because I needed another horse to focus on otherwise, I would have spent all my time energy grieving for Star. Not a day goes by I don't think of her, though, and that was two years ago.
Stella - sweet, timid, elegant, lovely, lively, amazing
Luna - large, unattractive, naughty, adored