Answer: Loving your neighbor as yourself means that our entire world (the still, vegetative, and animate levels of nature, as well as humanity) and our entire universe become an integral part of you, "as one man with one heart." You connect everything to yourself and perceive it as your "self." Otherwise, you don’t exist!
Our egoism separates us, but above it we must receive a force from Above, the desire and ability to feel every person as myself and even more than that. I have to feel that this is all me. However, this "me" is not an egoistic feeling because the hatred between us remains and even grows. I unite with others precisely above this hatred, and in that case they are called my "neighbors," or the people close to me.
A "neighbor" is a person whom I hate, but at the same time I "love him as myself." "Love will cover all sins" means that the previous hatred remains, but love is added above it.
In our world everything is driven by one egoistic desire, whether in reception or bestowal. In the spiritual world, however, we find ourselves between two opposite forces: bestowal and reception. Egoism grows, but the quality of bestowal emerges parallel to it. These two qualities enable me to reach the sensation that I am standing before a mountain of hatred (Mount Sinai, which comes from the word Sinah – hatred). However, prior to that I have to go through "Egypt" – the slavery of egoism, the Pharaoh. I have to come to hate it and then run away from it, searching for the force to correct it.
When I stand at the foot of the mountain of hatred toward my neighbor, I have to say whether I really am ready to unite with others, to love them above my hatred, and to become as one man with one heart. If I have gone through all the blows and plagues of egoism (Pharaoh) and I feel that I have suffered sufficiently, then I agree to it! That’s because I hate my egoism even more than I hate my neighbor.
I agree, thinking that this will enable me to reveal the Creator. Eventually, however, I understand that love and bestowal to my neighbor is what fulfills me. I no longer demand anything but this. This action in itself fulfills me, and that is how I become equal to the Creator.
From the 4th part of the Daily Kabbalah Lesson 10/3/10, “The Love for the Creator and Love for the Created Beings”