I put Pop!_OS on a laptop for my (elderly) mum and she used it for years, never had any issues, every now and then I’d tell it to update to the new version and everything was just fine. In the same time period I would have had to fix a windows install several times.

I would say tell him, it might suck but another aspect is your wife might want to find her biological father in the future. It would be weird to do that without telling the man who raised her I think.