I think I like your mother-in-law; your wife has God on her side. 'Gotten' is so ugly!
When I first moved up North in the UK [which is actually in the centre of the country], I used to wince when people said "I'll be working
while 5 o'clock" as elsewhere people work
until 5pm. I'm used to it now, but still don't use it. Amusingly [to me] it seems that Windows computers have a Northern feel to them, as they say "please wait while your computer shuts down".
I always find it a bit ironic when
Brits complain about Americanisms such as 'gotten', because American English is actually much closer to old English than British English is for one reason or another. Gotten being a prime example and period [in the full stop sense], another word people complain about used to be used in the UK but then fell out of favour for a while and is now seen [by some] as a horrid Americanism.
I read a piece by the author Joe Haldeman about the writing of a story he set in the mid 1800s and the unusual problem he encountered. A lot of the language that was used then had fallen out of favour and then more recently back into favour. This meant if he was truly accurate in the words he used, then it would seem wrong as a lot of the words are now seen as modern inventions.