How lucky you have been to have known such a man! It sounds like he is leaving a wonderful legacy of good deeds and wise words. He is not gone forever as his existence changed, at least your world. Remember him and share all your happy memories of him. Grief affects people differently. Express all your rage, sadness etc at the funeral, thats what they are for. Then after, keep his memory alive and listen to others share their memories of him. Sorry for your sadness, I hope all goes as well as possible.