Yes, you are now very hard. But still try to call for help common sense, logic. Say to yourself: "the Irreparable has already happened. Tears and sorrow is nothing to fix". Think about who will be better, if you are hopelessly undermine their health or psyche? Certainly not your family and friends. You have to take yourself in hand, at least for the sake of preserving the memory of the departed.
Very often such a difficult experience is the result of guilt. For example, you said something to hurt the deceased or did not pay sufficient attention, care. Now, you continuously think about it, you suffer from belated remorse, plagued by remorse. This is understandable and natural. But again, consider this: even if you do blame the dead, grief is the best means of atonement? There are so many people in need of assistance. Do something for them, help. Smoothen the guilt with good deeds. You will find where to apply their forces. Incidentally, this will help to distract from painful thoughts, the pain.
If you are a Christian believer, try to find solace in religion. After all, according to Christian Canon only the body is mortal – mortal shell, the soul is immortal. In cases where you are very grieved at the death of a child, remember the words: "Whom the Lord loves – He earlier calls to himself." And that baby will surely go to heaven.
Pray for the deceased, often bring prayer lists at Church. If you feel you are still not able to let him go – be sure to talk with the priest. Feel free to ask all the questions that bother you that you want to answer. Even this: "If God really is good and just, why did this happen?" Often, in order to calm down, first it is necessary simply to talk.
Try to convince yourself that argument: "He loved me, he would be very saddened if they could see how I am suffering." Sometimes that helps. Is there another good way is to head out to work. The more time and effort it takes, the less remains on painful thoughts.