Is she one of those women that it's not worth arguing with?
I think that this is encouraging and discouraging at the same time. Because - generally - how a man speaks and interacts with his mum is how he will speak and interact with his wife, once the honeymoon phase has worn off.
So that in due course if you say something that's batty, your husband is likely to stay silent instead of getting into an argument with you.
The discouraging bit is that this indicates that if someone is trampling all over him in life outside his family - eg at work - your husband may not be good at being assertive.
It is a breath-takingly rude thing that she said. Some people are rude and lacking in manners. With rude people, some have a heart of gold underneath it all, whilst others have hearts rotten to the core. And some are in the grey area inbetween.
Do you think that your mum in law actually genuinely loves you? Or do you think she's the sort to agitate to get your husband to treat you badly or to leave you?