I know someone who makes a living out of lying (most jobs you can't get away with it but he finds ways). He lies to everyone. Did you just lie to your ex or were there others? It may be some kind of sickness. Perhaps you can speak to a counselor about it and get help. If you admit to the problem and seek help, maybe your ex will at least speak to you again. Either way it is a good idea to seriously try to address the issue.