There is a mod called "Cowardly Horses", that might help you with your Problem from now onward. You can find it on Skyrimnexus.
To fix the issue at the moment try and kill one of them with the KILL command and ressurect them back up(Console commands).
Har, I did that with Shadowmere outside the DB sanctuary. I got tired of the damn thing fighting everything on the map. I didn't need to resurrect it though, it did that all on it's own, but at least it's stabled there forever, until I decide to use it again.