Don't hold anything inside
Talk! Tell whatever you feel about it. Becuase if you hold it inside(holding your anger and the things that you want to tell) it will hurt your heart.
It is a good therapy for you. If you feel like crying, then cry. Don't hold your tears. Just cry and get relaxed.
It is not the end of the world
Stop thinking like it is the end of the world. You are not the only person who has been cheated on. These kind of things are common in life.
Don't blame yourself
Don't blame yourself for that. Don't say things like,
It is because of me.
I am not good enough.
I have been cheated because I am not beautiful.
Just tell yourself that you are precious and he/she doesn't deserve you.
Hang out with your friends
Some like to stay alone and some like to hang out with others when they are sad. And hanging out with your friends will help you keep your mind busy so that you won't think about it.
Take a lesson from it
Bad things happen in our lives and the important thing is to take a lesson from them. Think about it!
Ignore what others say
They will talk about it a lot, ask questions or try to give advice, and some will even blame you. Don't listen the things that you don't want to hear. And the more they talk, the more you will remember and the harder it will be for you to forget it.