I know it's probably not the right thing to do but ever since I was a lil' kid I had a way of like blocking that shyt out. Like an aunt or uncle would pass and I would box it up in my head and lock it away. My family thinks I'm a cold b*stard cause they'd be consoling each other crying their eyes out and I'd just be there doing nothing.
Only time it didn't work all the way was when my pops died about 4 years ago. He was in and out of prison while I was growing up so I didn't really have a relationship with him. I didn't hate him or anything like my sister did, I was pretty much indifferent to the whole situation. I hadn't thought about that fool in years when my mom called me like get to the hospital you're dad's there and it's not looking good. I didn't even know he had cancer. I was like if I have a chance but I'm pretty busy and she's like no your grandma keeps asking for you don't be an a$$hole.
The whole drive over there I'm just thinking I guess trying to psyche myself into not giving a fukk. shyt like everyone dies eventually, he's not even really my dad, my stepdad is my real dad etc... So when I get there I'm in the mindset of just get this over with, you're doing it for your grandparents blah blah blah. I get to the room, my family's all crowded in there, they see me and part the way and I see him, you know with the tubes and beeping machines and all that...and I just crumbled. He went from a stranger to my dad in an instant and all the shyt I was telling myself to keep my composure went out the window.
He ended up sticking around for four days. He was unconscious but I went and sat with him every night when no one else was there. I caught him up about me and my sister, played him recordings of his grand kids, told him there were no hard feelings about him not being around. I have to say those last days I spent with him helped By the time of the funeral I was able to box it up and lock it away like usual.
I guess any advice I would have would be to make sure you spend some quality time with your parents. Make sure they know what they mean to you and just how much you appreciate them/love them. Let em know they were great parents who taught you what you need to know to survive in the world and be alright when they're gone. I'm sure that's something that worries parents about passing away. Maybe in the process of letting them know it's all good/they did a good job you alleviate some of the things bothering you about their eventual passing.
Damn didn't plan on writing that much.