How to believe in myself again & face the world confidence!?

With your chin as high as possible. Be as courteous and pleasant as possible. Kill them with kindness. Show them that you are mature and confident (even if you don't feel like it) and don't let any potential employers know that anything is wrong. Think of it this way, thank God you are not the poor chick he is engaged to! You are rid of this s sucking jerk and now are on to a better and happier life!