Why are you marrying into an family?
You are spectacularly naive and you will regret it.
I mean that kindly.
That laid back man who doesn't notice things is actually probably weak and will NEVER stand up to them.
The money is the least of your problems.
You are marrying a man from a toxic background who is cowered by them.
You are young and think love will conquer all, when the truth is it often doesn't when you marry weak men that are frightened of their bully parents, and have been reared to accept shit behaviour.
@Whokno post is a sensible approach if you insist on marrying him.
If you insist on marrying him, ask his immediate family and no one else, no friends, or other randomers.
If they kick off tell them their attendance isn't necessary.
Be prepared to go NC.
You will not want any children you might have around such toxicity.
Women like you often bitterly regret marrying into such a toxic stress.
No happy gatherings.
No warm and loving involvement.
No feeling you have an extended group of people who want the best for you and are genuinely interested in you.
Life is short and to knowingly tie yourself to such awful people is such a waste.
If you were my daughter I would strongly recommend you rethink this.
That you found it acceptable that his mother has been so rude and unpleasant to you for so long, and he doesn't seem to notice, should be a huge red flag to you.
Most women with boundaries and self respect would have run for the hills, and realised who needs this bullshit in their lives.
I mean all of the above very kindly to you.
Do you really want this?
A life with a man whom you are constantly having to discuss how rude, nasty and ghastly his family are?