This girl has pissed me off. Should I be nice tomorrow morning?

I have this friend well now we're not friends, and our friendship has been so rocky because honestly she has a very bitchy attitude. She wrote a status anonymously about me on facebook so I did also. She left her heels at my house and now I have to give them back to her tomorrow morning at college. Recently she has just been acting negative towards me so I've done the same and I just text her ya when she asked me to give her the heels tomorrow. I asked her if I can give them to her before class, she wrote the same thing "ya" to be smart. So when I see this girl, how should I act? Just nice to her when she's going to be rude? Or how? PLEASE HELP! It's tomorrow morning lol!