I am sorry to hear that.
If you read my website, then you know I have dealt with that, and recently too.
Grief is different for every person, and processing it is equally varied. What I can say about it is subject to my own predilections and thought processes, but perhaps they will benefit you.
To process the loss of the person: talk about them often. Think on them. Tell others about them. Whenever the opportunity arises. If possible write down the story of them, or paint it, or sculpt itโฆsing it. However you feel creatively inclined to share their persona, do so. It will be painful, but in the same way that stretching out a wound so that it heals properly, is painful.
To process that cold wash of mortality: go and explore life. It sounds odd, but I usually plunge headlong into physicality. Eat, drink, run, kick, danceโฆwhatever physical thing you do that wears you out so utterly that all your walls dissolve and you feel your own body. You have to feel your pulse, your blood, the fact that you live and that there is beauty in that.
To process the idea of death: go to a museum and wander through time. The continuum of history often helps one feel a sense of calm.
And as always, hold your loved ones closer for a time.
If you want to chat with me more directly, I am available.
I got my best friendโs tattoo after he died of testicular cancer at 24. The whole group did.