OP, for such a nice person, do you think it is actually normal for a mother to be mis advertising your husbands private business, his salary?
Kindly meant but I don't think nice people do that.
She's telling lies about your husbands salary to fit her narrative.
I certainly wouldn't associate that with a nice person.
I still think you have probably been conditioned by her for a very long time by virture of accepting her behaviour.
I think a lot of daughters would have firmly put their mother in her place as would a son in law.
I think you should accept your share, but I am at a loss as to how the relationship is repaired.
Perhaps continue with the family counselling but I think you should protect your child and yourself from her.
I would think some counselling yourself could be very helpful too.
Whatever her bonkers reasoning, she has caused you huge pain and tells lies about your husband.
Not normal behaviour at all.
I would continue to be very wary.