Those are also some of my biggest fears too. I honestly don't know what to do about it, I'm not scared of dying and being dead and not existing - quite the contrary, those are my most cherished desires in life.
I'm thinking about jumping a lot, just thinking, not planning or looking anything up... I've thought about it for a long time before too but went to other methods instead. I don't even drive so I'd have to find a way to get there which is like 20-30 mins away to the nearest bridge, and it'd have to be at night so no one really notices. I do have other methods but they just won't work for me, I don't have all the supplies for SN and methadone (I have a high tolerance too) and even if I did have it, I have gastro problems that would cause me severe pain and agony if I ingested poison, and hanging just never worked for me I tried dozens of times.