It's easier for everyone involved if your 'backup' person is a horse person. Someone who's comfortable with the idea of holding the horse and holding one for the vet.

Coping suggestions, hmmmm. Everyone handles grief differently. One person I knew didn't want to talk about the horse for months. Another talked my ear off with stories about her horse. Another just cried. However you handle traumatic, difficult, or sad events is how you should handle your horse's passing. Do you like to cry when you're sad? Do it. Do you like to sit alone and ponder the universe? Do it. Do you like to remember the good times with old friends over a few pints of beer? Do it. Or do all of the above.

I'm a big believer in the fact that people can take care of themselves. Whatever works for you is what you should do. The only thing you should NOT do under any circumstances is feel guilty or ashamed.