My response (cont.)
Empaths look at the amount of hurt caused by loss and say, "This is what this meant to me, this is how much I valued that thing and now I am grieving in equal amounts." Empaths examine their own grief that way, and they also take cues from others about how much something meant to them: "He seems to be handling this well, he must not have cared very much." But sociopaths experience grief in a much different way; it's like comparing apples to oranges. You will never know how much your sociopath cared about you or your relationship because you have absolutely no context for the amount. It would be like me telling you that he cared for you 10 martian kroners worth, or 10 billion solar pesos. There is no reference point for you to understand, no known exchange rate. And I think that is what you are really asking, right? Not does he feel sad, because I am sure if you were together with him for a year you would know that yes he does feel sad. What you are really asking is how sad does he feel, how does he feel sadness, and what makes him sad, and particularly whether he is sad about the prospect of your leaving him?
But more than just that, what you want is meaning. You want an explanation for everything that happened in the relationship, everything he said, everything you did together. I understand this about empaths -- it is not so much what happens to them but how/why that matters. Take hypothetical situation: an empath starts out with $100 in the morning, gives $50 to a homeless guy, and then gets mugged for the other $50. Or they lose the other $50 in a storm drain. They feel good about the $50 to the homeless guy and feel bad about the other $50. That is very strange to the sociopath, because both are arguably just a loss of $50. But here is the weirdest part! Empaths would rather have lost the other $50 in a storm drain than have been mugged for it. Why?! As a sociopath I see the justification for giving the homeless man the money -- you are transferring wealth to someone who will value the money more than you. But the same applies to the mugging! The money goes to someone who probably needs/values it more. The only arguably bad outcome is losing the $50 in the storm drain, which empaths feel fine about. But that's because to the empaths it is not the fact that $50 was lost in these various ways, but how it happened.
Similarly, because you are an empath, you will concoct a huge story for the relationship, an explanation for everything you were, everything that happened. You will rehash every memory, relive every conversation, even reread past correspondence searching for "answers." You will try to find meaning in this story that you piece together of what "really happened." You will look for motives, you will question everything you thought you knew about him and the relationship, and it will be very very painful. Your sociopath will not do any of this. He only knows that the relationship failed. He will only see the result, perhaps the most immediate cause. He will not suffer this rehashing pain, but it is not because he cared any more or less. He just cared differently, and he is emotionally evolutionarily advanced enough to not indulge in an elaborate investigation and revisionist history. He will grieve, and he will move on. And there is no reason at all to fault him for that. In fact, when you look at things this way, is he really the one that is causing you so much pain? You are devastated because the relationship failed and you are suffering loss. But you are in pain because you are a reactionary empath and you are making things worse by reliving and rethinking every tiny detail. You are overreacting and focusing on things that don't matter, like the whys and hows while he is focused on the true measure of success, failure, loss -- the what. I think if you are honest with yourself, you will see that your pain/disease is more autoimmune than viral. So no, I don't think he gets what "he has done" to you. I bet he doesn't attribute any of your self-inflicted pain to himself, and for good reason.
With all of this said, I realize that pain is pain no matter what the cause, and you are an empath so you probably can't be expected to do better than you're doing, and I understand that sociopaths are very difficult to deal with and that you have probably suffered a lot of frustration over the past year with him. I hope that you are able to quickly find peace and wish you all the best in your time of grief.