How can I get my ex to listen to me?

I was with this girl named Crystal and I had a friend named Alex. I didn't know Alex for a long time but I knew Alex and Crystal didn't like each other at all. And I don't know but one day Crystal came crying to me. I asked her what happen she said that Alex called her all these bad stuff and that she should do everyone a favor and die cause she was useless. I got so mad then Crystal told me that she knew that Alex liked me. So she came up with this plan that it would be funny if I pretended to like Alex. So 2 days later I got with Alex and slowly I started to fall in love with her. I mean she was perfect. She nice, beautiful, and always had a smile when I saw her. I would spent everyday with her and less with Crystal. 2 months past and I was still with Alex. One of our friends named Shawn had a party and we went but I had no idea that Crystal went as well. There was a band playing and Crystal stopped the music and everyone was looking at her. She looked at Alex and told her I was pretending to like her and it was all a joke. I couldn't believe it I looked at Alex and she ran out crying. The next day I tried calling Alex, I message her on myspace but she still wouldn't talk to me. Im so depressed, I can't stop thinking about her I even started to cut my self again and I broke up with Crystal. Please help me. . . . .