Each time you recall them it will hurt, an ache budding from deep roots that can never be removed. Every time you remember their laugh, every time you recollect a long past conversation, a favorite memory, a treasured embrace; you will long for them, seek some sort of reprieve. To think that the world goes on to turn without them will ravage you, when you let it. But this too, shall pass.
It may never heal, not completely, but the scar will become a part of you. When it does, you will see that these pain riddled memories are gifts. You will know that the more painful the recollection, the more valuable the moment. Cling to that value, rather than the pain. Memorize the message, the humor, the lessen or love you received rather than the departure. In doing so you allow whosoever passed to remain with and help to make you stronger, rather than condemn them to become the shackle and fetter that drug you into darkness.