I have been very, very lucky with my two Ds-i-L and their families. But I do remember how difficult was my relationship with me MiL; she never forgave me a) for getting pregnant (b for marrying him c) for being, as she saw it, from a lower class. Every other word was a sneer. When DSiL got married - "She is doing it properly, of course." (She had discovered the pill...)
They lived in Germany, and did make the effort to come over regularly, only for her to express surprise at how lovely and well behaved the DC were. we couldn't afford to go over often, because of course we "hadn't made the best start in life."
I am, however, very glad that I never said anything, just bit my lip. My goodness, what a rant.