I lost my Grandfather on April 9th this year to sepsis from open heart surgery the man who became my father and took me and my siblings in when my parents failed me. Trust me when I say your wounds will not heal until after the funeral. I thought the same as well that I was fine. It was like i was dreaming, until I actually attended the funeral and saw his body. That's when it hit me that I'll never see him again and I started to remember all the memories we had. Don't be afraid to cry at the funeral let it all out, but at the and of the day remember who he was don't let grief destroy your image of him.
I still think about him everyday, but Me and my Grandmother are doing okay. I still tend to avoid Funerals and talks of funerals because they make me dwell on that day.
It does get easier surprisingly, but I'd still give anything to talk to my Father one more time.