IT HAPPENED

One of my sims once took a DNA sample of a sim who was getting old and didn't have any children, and because they had maxed out Science skill, they cloned them. The clone was a newborn baby. It grew up normally, like every other baby sim. I'm not sure at what level Science skill it happens but there is one of the levels where your sim automatically receives a DNA sample of themselves in their inventory. My sims routinely store that in a World Adventure chest, although now I've read HotBlackSand's stories I realise the toy chests might be able to be used ...

Anyway, your surviving sim could build up their Science skill, high enough to take a DNA sample of the ghost of their unfortunate spouse, and then build the Science skill high enough to clone them. That's if you're into trying to find interesting workarounds rather than restarting. Such a fun turn of events, interesting to use. I don't think the clone of a ghost would be a ghost, or would they?

You'd be entitled to bonus points for having the ghost of a sim who died that way in a traditional legacy.

And by the way, you have a very charming house! The sort that's fun to play, so nostalgic.