my father in law beat up my husband

So this is a long story, so if you stick with it to the end thanks in advance! 
So this weekend I went away to go to Colorado with my grandma to meet my mom and have a girls weekend. While I was gone my husband was hanging out with his family. His dad has always been a real jerk to his mom, he's never been physical but treats her Iike a slave. Demands that she does certain things for him, like getting a beer for example, and gets very grouchy if she doesn't. So she waits on him hand and foot and gives him everything. Me nor my husband have ever liked it but it's his parents so we never really said anything. Well while I was gone and he was over there visiting he was playing a boardgame with his mom and during the game his dad demanded that she get him a beer. (both my MIL and FIL, in my opinion, may be on the verge of being alcoholics) so even though she's playing this game and he's just sitting on the couch she gets up and gets the beer. That must've been a breaking point for my husband because he then says to his dad something along lines of "you need to start treating Mom better.. you treat her like crap..." well at that point my FIL gets up and pushes my husband and puts him in a chokehold. My mother-in-law managed to break it up, for some reason at that point my husband didn't leave but was going to try and work it out with them. Well they have a conversation, and it turns into my FIL admitting he needs to change and needs to treat my MIL better. At this point my husband brings up the drinking and how many times he has said he was going to change and stop drinking and that has never happened. To which my FIL replies that he is a grown man and can do whatever he wants. I'm 26 weeks pregnant, my husband asks if they ever intend to watch our daughter. Of course they say yes. So my husband asks if he's going to stop drinking. He says now no, so my husband says that they won't watch our daughter if they can't stop drinking. Well of course that hit a nerve, and so my FIL goes after my husband again, this time hitting him. Then physically throwing him out of the home. My husband wants to leave but he brought our dogs over and they were refusing to give them back. So my husband ends up calling the cops, The cops come my husband tells his side of the story. Well when the interview My FIL he tries to tell the cops that my husband started it and they should take him away to jail. Now at this point My FIL is beyond drunk and doesn't know what he's saying, my husband is sober. So thankfully they believe my husband so he doesn't go to jail while I'm out of town. They finally give our dogs back and my husband goes home. My FIL continues to text him through the night saying my husband is a POS and he wishes he was never born and all these ridiculous things. My husband just ignored it, but he's really torn up, he thinks it's all his fault and should have never tried to stand up for his mom. I know he did the right thing something needed to be said along time ago I just can't believe someone could hurt their kid. Now two days later, My FIL is texting us like it's NBD and that they just need to sit down. But my husband is still really hurt. These pictures are from right after, they are so much worse looking today, 😢 it makes me want to never see them again, but I want my kid to know their grandparents too...