Sorry for what you are going thru right now with your father.

Regarding this work project...
I would not blame your former supervisor. That has a high probability of not ending well. He won't remember it the same way you remember it (or at least won't admit it).

Just a suggestion-

Talk to your new boss and tell her you believe there was a misunderstanding on what you were to do on a project you recently finished. By the time you came to question the direction and realizing there may have been a misunderstanding, you felt it was too late to change it as you were too far along.
It has been bothering you, and you would appreciate the opportunity to fix it.
Using your own words of course.