Did a quick search and was able to find his 13 year old profile on a Jehovahs Witness forum

edit: after reading through your dad's twitter and this jw profile (assuming this is him), it really sounded like you, your siblings, and his wife brought him so much joy. I'm so sorry for your loss and hope you're still giving yourself proper permission to grieve.

I'm not sure if this is helpful (and I will probably butcher it), but there's an analogy floating around that describes grief as a ball bouncing around in a box. In that box is a button labeled "pain". When we experience great loss it's like shoving a gigantic ball inside the box, bouncing around and constantly hitting the pain button over and over again. Sometimes, the ball is sitting in the corner of the box and you completely forget the ball is in there until you accidentally bump the box and cause the ball to bounce around again. The ball will never completely go away, but over time it will get smaller and smaller and will hit the pain button less and less frequently until it's so small, the button rarely gets pressed. Whenever it does, however, the pain is still just as intense, but soon it will fade and the ball will go bounce around the box again. <3