I think you could have stood your ground by simply asking for the key and not getting pulled into all the other stuff that you did go into?
I'm not doing great myself in regards to my H so I don't have a leg to stand on... but, ultimately if you don't want her there just have the locks re-keyed?
After its done just let her know that if she needs anything she can work it out on your schedule? You shouldn't keep her things indefinitely but don't threaten to put them out on short notice.
