Tell her you really care for her and hope she will be happy. Wish her luck, take your stuff and ask her what it was she wanted to say to you. Get everything you wanted to tell each other off your chest, good & bad. If you part on good terms give her a hug if it is welcome. Then say goodbye. I'm sorry it didn't work out for you.

It's a good idea to have something else planned to do after she leaves on Sunday. Maybe you could go to a friends house, hang out and watch a game.