How can I help my friend?

So my bestest friend unfortunately had to deal with a pathetic excuse of a man that doesn’t deserve to be called a father and thankfully her mother and her are living in a different home and she doesn’t talk to him often. But he has done many horrific and disgusting things he is a narcissist that neglected his children, bullied them, tried to get them to do weed (her brother is now addicted to weed but she isn’t and has never tried it thankfully) he physically abused his kids and wife, and one time I think my friend told me he 🍇ed her mom. That’s not even everything that’s just to give you an idea. But he has had the cops called multiple times bc of this abuse and he hasn’t been charged with anything. But today my friend texted me pictures of her conversation with that guy today, for her privacy, I’m not gonna quote or get too specific but idc if I could, I would expose EVERYTHING abt this man bc he deserves to be locked up and if the law isn’t doing ANYTHING abt him, the public should at least deserve to be warned abt him but I don’t wanna have my friend’s privacy exposed. She basically told him that he doesn’t respect her boundaries and when she told him her boundaries he said that boundaries were for snowflakes (this man is DANGEROUS!) and he was saying basically that kids don’t get to make the rules and claimed she was saying that they should. He also said “kids don’t get personal boundaries” he also claimed that she was fighting a one sided war with him he was asking where the conflict was between him(he knows damn well) and my friend told him that he 

1). Compared her getting a job to world war 2 (work or die)

2).when she went on a date as a young teen he proceeded to tell her abt how he lost his virginity at that age (CREEPY AS HECK THE JUSTICE SYSTEM NEEDS TO GET THEIR ACT TOGETHER THIS GUY IS GENUINELY A MONSTER) 

3).when she started working out and getting more muscle he called her trans 

4). When she was talking abt her friends he called her lesbian 

He decided to respond with “I was making jokes” I have NEVER felt SO MUCH ANGER FOR A GUY  I DIDNT KNOW I WAS CAPABLE OF FEELING THIS MUCH BOILING ANGER 

She basically told him tho that the conflict what everything he did and how he thinks he’s above everyone and she let him do that in silence. 

He said “that’s how I felt with things I’m uncomfortable with” the freak does that mean? 

What he said next is horrifying and I’m exposing every exact thing he said except if it mentions something personal to my friend or her family:

“ You are the most hurtful disrespectful child I have ever seen and you need your ass beat!

One day I hope you know what struggle really is. I hope you know what pain really is. I hope you know what pain you have caused me.

Fuck dinner you shows me exactly who you are your just another cold hearted bitch just like that cunt mother of yours. You have removed yourself from my family don't contact my mother or *family friend/family member’s name* you're not related to them anymore according to you. I'm done trying to be there for some one so self centered and thoughtless as your self!

Goood luck *friend’s name* change your name since you got it all figured out I'm out! The arrogance you shown is unforgivable. I'm ashamed of you that you think you are anything close to being adults”

She is genuinely one of the kindest sweetest person I’ve ever known. I wouldn’t blame her if she acted out often due to this trauma he caused her but no she is the most responsible mature person I know she doesn’t deserve a single ounce of anything that happened to her and her mother is also very sweet and kind she didn’t deserve any of this bs. He’s lucky he even gets to talk to my friend a little bit. I told my friend “ Also yes he went through some bad horrible things but none of that bs can amount to the pain he has caused you and your family none of that excuses shit I hope one day he learns and understands just how much he fucked up and when that day comes, he shouldn't come crying he doesn't deserve any place in you and ur mom's life the only place he deserves to be is prison where he will rot

He's a pathetic excuse of a human being whenever u get the opportunity to safely do so, block that dumbass” 

Idk I might be being dramatic but him saying “…you need your ass beat!” Is a threat and I wish I could contact law enforcement bc that could probably get him in trouble if the cops were competent in any way but she told me that law enforcement hasn’t done anything abt what he’s done and I don’t wanna cause for stress and causing her and her family to reopen trauma. But I can’t just sit here and do nothing! I have to act in some way. And I’m extra concerned too bc her brother is living with him. Her brother can’t go back to them tho bc he’s crazy too and beats the crap out of his mom and is just a bad person but I blame the dad for a lot of it (I still acknowledge it was her brothers fault and he’s in full control of himself but the dad definitely caused him to be the way he is) but he needs to get out of that environment bc I can only see that making him WORSE I need to know what to do