Of course, you are upset now - your ex dumped you, your relationship has ended, and you really want to get your ex back.
However, there are a few things to consider before you rush into trying to make contact with your ex - especially since your ex dumped you for someone else.
You need to figure out if your ex just got tired of being with you, or if there was someone else that your ex was seeing, that was the cause of the break up.
Also, as your ex probably doesn't want to talk to you right now, you need to find these things out some other way.
The very best way of course, is by speaking to your mutual friends.
There is no doubt that your ex has said something to them after the break up, so talk to them, and see what you can find out.
You must also remember that what you find out could go either way, so you must be prepared for what you hear.
If your friends tell you that your ex is simply confused and needs some time to think things over before making any sort of commitment, then you're lucky.
This means that your ex is still interested, but needs to figure things out first.
All you have to do in this case is give your ex all the time he/she needs until the time is right, and then you can take steps to get your ex back into your life again.
However, if your friends tell you that your ex IS interested in someone else, then there is really very little you can do about this.
You can't force your ex to feel for you the way you would like him/her to.
You might be tempted to just stay friends with your ex, so as just to see him/her from time to time.
Don't do this though - you'll only prolong the misery you are already going through - rather just accept what has happened and don't try to get your ex back - just carry on with your own life.