Many of us here understand the panic/fear/anxiety attack that prevents us from doing something, along with the aftereffects of "hiding."

I was going to suggest that you not think about going back to work, but that you would "stop by" and say hi, only. If that went ok (no, not easy but doable?) then the next time, stay a little longer, or come back for lunch or such. Piecemeal it.

Let us know how you're doing, ok?