I agree to a certain extent. Take the car keys. Depending on the living situation (is your name on the lease, is her name on the lease, or are both names on the lease), set a timetable for the two of you to either move into your own places again OR work out the relationship - since you say this is what you really want.
On that note, is the relationship really worth saving? Is she even willing to work on it? If not, there is no saving it. You HAVE to talk about it for the two of you to have any relationship (even friendship) at this point, because if you don't you're always going to be pining for her and she is always going that you're there just in case she winds up alone at any point.