Sometimes actions have a "period" between them, not a "semi-colon".
Your husband behaved violently and threatened you; you called 911.
The police charged your husband.
Your mother-in-law may or may not help your husband pay his legal expenses.
The only linkage here at all is that when your husband attacked you, you called 911. ( A wise thing to do, too, to keep yourself safe and alive.)
The fact that YOU called 911 did not make the police charge your husband. They charged him because he was violent. They would not have charged him if he had not been violent.
The fact that your mother-in-law may enable your husband by paying for his legal expenses is NOT YOUR FAULT because you called 911. It is her choice to make and the only reason she has that choice is because your husband chose to be violent.
You can't link actions that are not cause and effect because they make you feel guilty. It doesn't work that way.
In the same way, you can't interject emotional interpretations into a series of actions and thereby discount the actions. Your husband got violent with you. It doesn't matter whether you think he didn't mean to, or you think he had a bad childhood that forced him to do this, or anything else. Actions are actions. The facts are the facts.
What is done cannot be undone. He repeatedly crossed a threshold of behavior that is unacceptable, and that is a scary fact no matter how much you love him and want to trust him. Your boundaries are solid, but beware and be vigilant. We all care about your safety and place that above our concern for his feelings and our hopes for his recovery.
Said with empathy and compassion, take what you want and leave the rest.
ShootingStar1