That is very sad.

Lucky for me my little cat will never die, so I don't have to worry about that. (I'll keep telling myself this, please don't disabuse me of my notions.)

I find that DOING things like bike riding, particularly with traffic, has the remarkable effect of re-caging my attention on what I'm doing. Everything else disappears until it's done. Particularly flying the jet; once I strap in, all the other concerns go on hold.

You may want to simply try. A lot of your fear of going out may simply be an expression of grief and a reluctance to do anything (often associated with grief). I may be wrong, but you too may find your attention where it needs to be in a big hurry.