Shalom in Yeshua Cami, and welcome back.
It is quite normal to feel sad when we think of our loved ones. That's being human!! None of us like the feeling of loss but what we do is try to think of the positives. We remember the good times, and we look forward to re-uniting with them when its our time to go home. It is something to look forward to, and something none of us can avoid.
When we cry over them, we are actually crying for ourselves. We feel the pain and we miss them. (Notice, WE feel, and WE miss) The what ifs always come to mind, and then we punish ourselves with guilt. In your case you say you have forgiven yourself, but deep down I can see that you still harbour these feelings, otherwise you would have let her go by now.
Your grandmother is happier than she could ever have been on earth and you should think of her bathing in the loving rays of the Father. If you try to do this you should start to feel happier about where she is. Then start looking forward to the day you can put your arms around each other again.
May God bless you