That made me laugh really hard. Maybe it wasn’t a little wang, maybe it was a nipple. I dunno, it wasn’t particularly huge, it was just singular in nature in the right place…
My experience from little wild critters is they don’t like being flipped over and examined… so I sort of waited till the teeth would no longer be an issue… 
Poor little guy 
Definitely a cutie, sorry things didn’t turn out well. But good on you for taking care of him.
Over here we call them tree rats. They are bigger and tougher than our native red squirrels and are driving them to extinction.
Get a kitten of similar colouring, and start calling it Rocky.
If your wife asserts that it is a kitten and not the squirrel, give her sympathetic but patronizing look, ask her if she is feeling OK, pour a bath for her, and state “We’ll just have to agree to disagre on this one.”
Be sure to get your vet in on it before she takes the kitten to the vet for the first time.