If you still can I'd cut a good chunk of her tail hairs off and braid a keepsake for yourself. I sent my gelding's tail hairs to a lady who made a horse hair pot from it and braided the leftover hair around the lip of the pot. You can choose the color beads so I chose my show colors. I think it helps to have something that was there's to help remember them by.
Very sorry for your loss. *big hugs* I wish there was something I could do to take the pain away. You just have to love them all you can for as long as you have them because you just never know. I truly believe everything happens for a reason even if right now you can't see what that reason is.