Don't worry somehow it will work out the best way. I mean it is messed up that she said you can use it and now is back peddling especially since the car has just been sitting there since May!!! Whatever!! LoL. You know what the crazy thing is that I learned through all this is that the ones you thought would kick you while you're down are the ones to help you back up and vice versa.
Don't be too harsh on Rose maybe she told you that you could use the car before she even checked with her H and now it's causing problem with them.
No matter what, you will figure out a solution and be A-ok!!