Leave.
My marriage was like yours 22 miserable years I stuck it, the thinking at the time was that it was 'better' for children if you stayed togesther.
Lies. Its not.
Mother was no support at all, told me 'You make your bed you lie on it'
I didn't know how to escape, no money, no support and no confidence.

I did get a divorce in the end. One of the best days of my life.

My MIL was a b##ch too.