What should I do? I need the valuable stuff she has on her but I can't carry all of it and if I fast travel away to get someone else to follow me, the body will disappear. Also I can't reanimate her because she's too powerful!

Just how far are you from the nearest town?

Whirlwind sprint to the nearest town? Reload another save.

I'm far away and all my saves are around this area.

I'm kind of near Ivarstead. Is there a horse and carriage there?

Ok I've managed to slowly walk there. I gotta find my horse!

Unfortunately no there is not. Are you perhaps a werewolf or vampire lord?

Nope, but I am on my horse now so getting to Whiterun will be easy. Quite a scare I had.

Cool, you can fast travel while overencumbered when you are on a horse.

Well glad to see you resolved your problem, sorry I couldn't be more help.

Literally just dump all of it on the ground somewhere outside where you will remember it. Outside cells do not respawn and it is safe to leave things lying on the ground, though NPCs could possibly (unlikely) pick them up while you are away. I left a lot of valuable stuff in the middle of the road near Windhelm and nobody ever took any of it.

It's ok haha