Wow. You have really been hurt, and have become so bitter to you cannto see or hear what I am trying to share with you. Jesus volunteered for the mission He lived out and died for. What makes you think Your Grandfather is dead? many friends and relatives of mine have llived and died whether or not I think they deserved it. Some died natural deaths in their old age, some prematurely; some in war; some by awful diseases; some died in car accidents and some died by their own carelessness.
Are you not aware of your inner self, that person inside your hert and mind tht never dies? Some call it one's soul, but nevertheless, a person never really dies, including your Grandfather. (I assume you and he were very close, and his parting deeply hurt and still does.)
Because of these things you cannot see, let alone, receive, the overarching outcomes of Jesus' life, death, and resurecction. You ache every time you think of your Grandfather. and it's a blnding pain.
Jesus suffered too. When His friend Lazarus died, He wept. He suffered many other things, mentally, physically, socially, and so on (see Isaiah 53, https://biblehub.com/nlt/isaiah/53).
"...we do not have a high priest who is unable to empathize with our weaknesses... (Hebrews 4:15)
I could share with you a couple of my life experiences that you might benefit from to begin to open up to the reality of eternal life, but they would make this response an even longer essay... and I don't even know if you would want to read about them.