This rings true to me in a lot of ways, too. Anxiety disorders make you conjur up and fear just 'bout every unknown possiblity in any given situation. The not knowing and the "what-ifs" are often worse than reality, in my experience.
Oh gosh, that spiral downwards when you're thinking about your own mortality is never fun. For me, I start to worry about everyone I'd be leaving behind, especially my partner. I'm scared for myself too, but... I don't really believe in an afterlife, so I just imagine it'll be like before I was...
That is definitely terrifying to think about. I didn't even realize it was a thing until I saw an episode of House on it years ago and discovered a new fear.
This is a tough one for me to answer, because I'm afraid of so many things, heh. Spiders, heights, dark places, small places, the horror genre in its entirety, the ocean, even my own dang shadow sometimes... My list is truly endless.
Being completely and utterly alone though. I think that...