Why is my wife so angry at me after i gave her the divorce she kept on asking about?

My wife cheated on me and left me for another guy. She kept on insinuating that we should get a divorce. We kind of put the divorce off for a while, but we were seperated. One day i finally decide to file for divorce and we both went to the Court. Once i filed for divorce, and are waiting for the court date..she is so angry at me everyday, wont talk to me, is always pissy with me. And i dont do anything, i moved out, have a Girlfriend and just pick up my son and hang out with him. Why is she pissed at me? I dont even talk to her unless it is related to my osn. I would have thought that she would be happy, now that we are getting a divorce and she is with her new boyfriend.