Hey Elf! That was funny ... monster-in-law indeed! Ha! Fortunately both of mine were wonderful!
It isn't that she's bieotchy or anything. It's just that she's so pretentious. It's what things "look like" that are important to her. My sister-in-law, for instance, lives in a beautiful home (with an elevator!), drives a jag, goes on trips and cruises, eats in fancy restaurants, wears designer clothes, etc. The fact that she's living on the edge and drowning in debt means nothing. All the MIL sees is "my successful daughter....".
We, on the other hand, live a pretty much hand-to-mouth existence, but she still brags to her friends about me being an entrepreneur (ha! right!) and how the DH is "retired". Makes me nuts!