Sympathy is known to be a shared type of feeling that can be felt towards another person. For example, if you know that someone is going through hard times, you cannot help but feel sympathetic towards that person. You feel pity because you know that the person is going through some tough times.
When you are feeling empathy, this means that you are placing yourself in the position of the person. You are feeling what the person is experiencing because you are identifying with the feelings of the person. Being empathic is said to be heartbreaking mainly because you tend to feel what other people are feeling. They sometimes feel the emotions of more than one person all at once.