A definition of empathy will be a projection of one's own personality into the personality of another in order to understand him better. When you see the world from the other perspective you can be sensitive to his joy and suffering, in the case of sympathy you will only be sensitive to the suffering. True empathy helps to understand others better this is the way to make healing relationship, if you pay to much attention to yourself and your impact on the others you have a very limited perspective that will not help you with your relationship. Try this exercise :

Imagine a situation that involve a friend of your examine the situation as you know and think of it, then put yourself in your friend shoes and imagine the situation from your friend's perspective. Now, imagine, the situation from a third observer. If you do it , this exercise will give you greater perspective on the way you interact with others.

Usually, there are 3 level in communication : what is said, what is meant, the emotional need being expressed. If you use empathy you will be able to address directly those emotional needs, you are communicating and your relationship will improve a lot this way.