Typically, the most challenging aspect of blotting out your ego is to confess that you were wrong and essentially to take responsibility for whatever caused the romance to crumble. If you want to get back with your ex, you'll have to toss your ego out of the window.
If your partner has bruised your ego, the best thing to do would be to forgive him or her for it. There's no need to put a loving and healthy relationship on the line because of an ego problem. Even though your ex might have hurt you deeply, you must grant forgiveness for the sake of your relationship. Sometimes people say things in the heat of the moment; at times like these you should ignore what your ex has said, for the benefit of the relationship.
Focus on your partner's positive qualities and on the positive aspects of your liaison. Your ex might well be influenced to follow suit, providing an envirinment that is conducive to strengthening the relationship. You will then be ready to take your relationship to a higher level.
However, if you are the guilty party in saying hurtful things to your ex, you must swallow your pride and go and make an apology. Don't be ashamed to admit that you regret your actions and that you are sorry. Explain yourself to your ex in a quiet and relaxed manner, making sure that you are honest and open. He or she will surely appreciate your integrity and the attempt you are making to salvage the relationship.
Notwithstanding the effort it might take to acknowledge your mistakes, setting them out in the open is a gallant thing to do. Make it clear to your ex that the mistake will not be repeated. While this should help to bring your relationship back to normal, your ex might not, however, be as accommodating. You will have to be prepared for that possibility.
Recommended reading: "Ex Back 101" by relationship expert, Michael Martins.