Thank you for sharing this, Johnny. Death is definitely a scary part of life, especially when it's about those closest to us.
If I might offer a word or two that I hope will help? There is so much power in our words and in our thoughts, as I know you know. As long as you keep saying how horrible it's going to be when your parents pass and you have to sort out their belongings and house etc., you're making it worse for yourself. You're reinforcing the stress and awfulness. You're psyching yourself up to come apart when that times comes.
You cannot avoid it - unless you die first (heaven forbid). So the best way to deal with it is to start preparing for it now, and you can do that by changing your thoughts about it. Tell yourself that it'll be sad and difficult, but you'll get through it. You have a bunch of siblings. Yay! Lucky you! You won't have to go through it all alone. Think of that as a huge blessing (because it is). Doing all of this by yourself would be awful, and not having anyone to share the load or the memories or the laughter or the tears would be far worse than getting to remember all that stuff with your siblings.
Start preparing by having conversations with your parents about what they'd like done with their stuff, and do they have a list, and who would you need to call etc. Ask where they keep their Wills. Who is the lawyer, which funeral home, what music - everything.
Prepare by having honest conversations about how much you love them. Get to know them NOW while they're still here. Ask questions about their childhoods, their backgrounds, their weirdest little memories.
There's a lot you can do now to changing your thoughts and telling yourself that you CAN and WILL cope with it very well when that time comes. You will walk through it a day at a time, and it will all be okay. Because it will - I promise. Both of my parents are gone - and my only sibling. I'm the last one left. And I'm still standing.
Thanks for sharing this, Johnny.