glad you're here to vent a little
I'll offer you this - when one person observes another person being abused, that first person is being abused as well. He or she might not be the one being cursed or reviled or struck or beaten, but it is an abusive situation for that observer nonetheless.
When your husband, more than likely after how many similar scenes with his mother-in-law, your mom, saw her in action, and he called her on it - you don't describe how he did that exactly, I am imagining maybe a "Hey whoa, no you don't" minimal type thing? - and then she erupts -
She proved exactly what he'd had enough of and what you've absorbed your entire life - she is entitled to exploding and hurting people.
If the issue is that he said something without seeing how you felt about it first... . and the comment he made pretty much led to this nc you've benefitted from, yet you have very mixed feelings about it -
Don't hold the wrong person accountable for your mixed reactions. I do get what you mean - at some point you had hoped to address her behavior yourself.
As someone who never had a single person stick up for me like he did for you, and that's not your problem, just how things worked out for me amidst my siblings and the man I was married to for almost 30 years when my mother would do just like yours -
You know how you envy something you never had - appreciate your advocate if you can. He loves you, sick and tired of his own home being waylaid with filthy ugly hatred... . and said so.
Having a maelstrom of emotions about it is due to her abuse I think... . all of us have radars that are really way way off kilter.
I'm sorry it sort of blindsided you.
I'm glad you brought it up.
And maybe most importantly, have you told him it left you a little stunned, that he said and did what he did?
I think if he reassured you it was for the health and welfare of his family and his home, you could maybe lay this burden down.
I hope so.