Betrayed

On the weekend I was moving out of my house into my own place, it was also my best friends 23rd birthday. She had decided to go to Atlantic City in New Jersey again which we had done the year previous as well. I had told her two weeks prior that I would not be able to attend because I was moving out that weekend and had many things to attend to. On top of all the moving out issues I also had my Godson's christening party the same day as she planned on leaving for Atlantic City. We still spoke about everyday up until her birthday trip. I called her on her birthday to wish her well and she never responded. One day passed, then two and three. She has not called me since I did not attend her birthday party. We were best friends for four years. I have tried since to try and talk to her to discuss what happened, but things have not been the same. It has been four months that we have not hung out together. I feel betrayed and lost. All because of a birthday party.. Please