How did you deal with sudden severe depression?

I think the great variety of things that you need to do can be stabilising. That you have to and can shift focus. I really can't concentrate on monotonous tasks for long.

But I'd really be afraid I'd run any business into the ground where I'd have to meet with customers, no matter what. Just feeling awful.

I can easily react far too strongly in reaction to opposition, too, either wanting to give up or sabotaging the relationship. Fine or good for negotiations when someone "needs"/needs you, not for face-to-face customer relations. No direct (face-to-face) communication not initiated by me, for me.

I'd love to work in construction, though. I think. But I'd be no good at it. I am probably not meticulous and precise enough (edit: seems paradoxical, but I can't be a perfectionist about differences I can't see. What others find important to be perfect, I generally don't care about, I think).

Maybe demolition would be better. Also less customised, less discussion, less talk. No buying materials. Good for my frustration at times.