In its deepest sense, empathy is the ability to feel other people, experiencing a shared sense of connectedness with them. You and others are cut down from the same source of life, you are essentially the same being, experiencing individuality in this physical world. On the surface level of the ego act or carnal mind, empathy is having a sense of what other people are feeling. On the level of spirit, empathy is actually feeling what they feel. Emotions are energy that radiate outside the body that actually affect everyone else in your immediate area. When you are connected to your source this Radience is drastically more powerful, and the light that you emit from your being affects everyone else that crosses your path. In the same sense, negative emotions that are derived from the ego also affects those around you. And example of this is when you walk into a room and you immediately feel a sense of negativity. One person can effect those around them in a positive or negative way, with out even speaking a word.
Unconditional love stems from a sense of connection and oneness, a sense that you are another person. Love is experiencing the oneness of all life, which transcends all situations. You love those like you love Yourself. Your Self is love, and unconditional love is the experience of that. Unconditional love from a carnal sense is impossible. The ego is not able to love outside of circumstances. But when you can experience the Love of someone else's being, you are connected with them and no circumstances can take that away, no matter how bad. This is why no matter how much pain our children caused us, it rarely ever affects the love that we have for them. This is because we are connected to them on the deepest level. Experiencing connectedness with our fellow humans is what will change the world.
Words can never truly describe the experience of the spiritual life. They will always fall short, because spirit is beyond description. Empathy gives rise to forgiveness, which enables us to look past any wrongdoings or negativity. This is how Jesus can hang on the cross and desire that those people be forgiven, because he knows that the only reason that they could do this is because they don't know who they are.
Clear away the clutter in the mind, and sit quietly for long enough for your heart to open. In reality, you already are awake in spiritual being. Only the ego can sense any separateness. Disappointment that one feels when trying to connect with their source and being unable, only comes from the ego. But you don't have to change anything. Be aware of the separateness, know why you feel separate. Clear away all the excessive thinking through meditation and stillness and eventually your heart will open. You can't manufacture this, you are this.