Ended it with this girl about a month and a half ago. It was long distance and I told her that things will not work. And we have to go our separate ways. I did no contact in the mean time, not a single word.

Now I find out that she will come to my city and stay for a while in the same building as me, and we have the same circle of friends. So at some point I will have to meet her again.

How do I act. Friendly, flirt with her. Give her the cold treatment.