It's only a matter of days since your break up, and you have heard via your friends that your ex is already dating someone else.
As distressing as this is for you, it has also made you determined to win your ex back.
You are also really angry about this and also quite jealous as well - you don't like the though of the person you love involved with someone else - it HURTS! Of course it hurts, and of course it will make you angry and jealous.
However, you have to keep your emotions in check if you want to win your ex back.
Flying in a jealous rage to try and get your ex back into your life is definitely NOT the way to go about it.
Also, remember that the other person has not idea what is going on, so it is very unfair to dislike him/her for no reason at all.
In fact, this person's feelings also need to be taken into consideration as well.
In any case, this relationship won't last for long at all - this other person is simply a crutch for your ex to lean on in his/her time of misery, that's all.
Don't sit around waiting for your ex and the new person to break up though - it might not happen for some time yet.
Just carry on with your own life for the time being - go out with your friends, be with your family, or whatever else it is that makes you happy.
I can assure you that, every time your ex sees you with your friends, he/she is gong to be thinking about you - a lot! All the good times you had together are gong to be popping up in his/her mind all the time.
At some stage, your ex is just not going to be able to handle it anymore, and will call it quits with the new person.
Any day now, you'll win your ex back.
He/she is going to call you and suggest that you meet somewhere to discuss the break up and the possibility of the two of you getting back together again.