I'm so sorry you have experienced such a terrible loss.I have not yet lost a parent to death(just to estrangement)but when I was 12, my oldest sister was murdered. She was only 16 and there were times I did not think I would live much longer than she had, I missed her so much and was so sad. I left school for a year; I had no idea anymore how to be in the world,or with myself. I felt overwhelmed by grief and anger.
One of the many worst things about death,I think, is that we have no control over it, either the death,itself, or its repurcussions throughout us, our reactions. We have no idea when we will be able to act and later feel "normally" again, and it is unbelievably upsetting. There is also a tendency to judge our own grief or to fear its own grief: telling ourselves, we are taking too "long" to get over a person's death, or imagining that other peolpe think we are.But no one,even ourselves, has a right to judge either the quanity or quality of our grief.It is all about the importance of mourning, which is part of the natural process of healing.
A good thing I had were 2 other sisters and friends,who recalled my sister well; we talked about her a lot.Someone else here said,and I completely agree,that talking about the departed one is a good form of therapy,and it also helps to keep the loved one animated for you and alive. Remember the special things, the special times,you had together: now you will have them all your life. If talking to a counselour seems an option, there are what are called "grief counselours" who work specifically in this field--working with people whose loved ones have recently died, or who still cannot get over a death.Seeing one helped me,years ago. If you are at all religous, there are also always members of your clergy with whom to talk about your loved one.
I like to think of myself as a sort of memory album/book,of my lost sister--whose pages I turn enough that she is far more of a presence in my life than an absence.And a parent--you must have a vast storage of memories,images, of them--far vaster than mine.It is possibly too early now, but later, try to remember that you are now the guardian of your parent's life,and that it is your pleasure and affection in your memories of them that allows them to remain indivisible to you, and almost as close,or as accessible, on this earth as you need them to be.