You absolutely have to tell her that your family indicated they don't want her there. She's deluded if she thinks they are going to treat her nicely now. But right now she thinks you are the roadblock to her going....if it was your condo, I sense you'd let her go, and it's reasonable since you are getting along. But your hands are tied since the owners don't want her there.
WAWs are weird that way...they don't want to be the bad guy to anyone, even the LBS, but sometimes reality has to set in for them. Be honest about this, and then keep going with what is working.
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer