Im so sorry for your loss, truly I am. It is very early days so yes, you'll probably relive that awful day for some time to come, and have nightmares too. But in time those memories will surface less often.
My elderly mum lived a few minutes walk away, died suddenly last year. She was my best friend and we chatted/saw each other very day. After she died, my toddler asked for her daily for months, and I had to keep taking him round there to show him she was gone. He thinks she has gone to the stars to be with granddad. And now he doesnt ask to go to her house any more. But he does, rather sweetly, want to be a space man.
My older child is bereft but in a silent, worrying way.
I don't think I'll ever get over losing my mum, and I will feel lonely now, forever. I guess you feel the same about your gran.
The crying will come. And then it will come at random times and be uncontrollable. Don't put pressure on yourself to grieve a certain way, whatever you're going through, that's normal for you and your situation.
In my experience don't expect too much of people around you in terms of empathy or sympathy. There are lots of good bereavement groups online, where people understand you won't be "over it" in two weeks' time.
I found some very helpful things to read and every morning I watch the sun rising (as, thanks grief, I now have insomnia), I think about my mum, and I imagine I'm planning my day with her and I still chatter to her in my head. And though she isnt here, I know she believed that in some ways she still lives because the love and wisdom she gave me, I'll pass on to my kids, and they will pass on to theirs and the people around them.
Today the sun is shining so brightly, and spring is such a beautiful time of year. I'll be outside in the sunshine, because if my mum is anywhere heavenly, she'll be in her garden with a cuppa. Maybe having a chat with your gran about whether there's going to be a late frost this Easter, and the mess in the Ukraine and what we can do to help, and somehow making a clever segue to natter about Tiger Woods' comeback.
You'll never be quite the same, but your love for your gran will carry you and you will live it, one painful day at a time, until things are bearable again. 