So even if you kill the people he sends you after he will keep giving you old turning quests. So that means I simply can't get the quest to turn my spouse doesn't it

you are pretty much screwed.
one of my characters after doing TONS of radiant quests now only gets sent to vingalmo now,reloading or doing anything else wont fix it either.
and like someone else said killing the people to fail the quest doesnt fix the problem,it will still send you to turn a dead person.
bethesda needs to patch this.