If the person calls and asks then I would tell her that the horse died but I wouldn't go out of my way to tell her. She has no need to know and the best that can come from it is that it will cause her some sadness. When something bad happens in my life I tend to not spread it around unless there is some way a person can help. The previous owner can't make your horse less dead, you don't like her, and it took her a long time to get over selling the horse. I see no reason to put yourself or the other woman through that.
There's nothing like the Rockies in the springtime... Nothing like the freedom in the air... And there ain't nothing better than draggin calves to the fire and there's nothing like the smell of burning hair. -Brenn Hill