Denial is an escape from reality. This was denial. I suppose denial is with me at this time too. Because I still wear the wedding ring that Kathy put on my finger in 1971. However, above all else denial is an unconscious defense mechanism characterized by refusal to accept the reality of death.
Depression is a deep sadness at the loss often accompanied by hopelessness of the occasion.
Depression results from an emptiness in your life that can't be filled. Some symptoms would be the inability to concentrate insomnia. Depression often requires professional treatment. Guilt wears many hoods. Very few of us escape feelings of guilt.