Dealing with Trauma and Family Issues: Need Advice

Been awhile. I'm needing advice. I'm 19, my 16 year old brother was just killed in a hit and run less than a month ago and in that same week, we had just become homeless. 5 days after becoming homeless is when he was killed. All of this trauma, grief, is really affecting my dad most of all and I'm becoming very concerned. We have a home now thanks to my mom, but it seems ever since we've gotten into our new home, my dad is losing himself, his mind. He's putting all the blame on my mom, my mom can never get a word out, he calls my mom names, says she's a bad mom, is starting to become controlling with her. Says she can't leave on her own to go get coffee or whatever it is, yet he's the one who tells my mom he drives down the road at 100mph and says he's going to kill himself. He is starting to get in my face whenever I try to defend my mom, doesn't let any of us talk yet all he does is talk talk talk. I literally stood there listening to him talk for 45 minutes straight without me getting a single sentence out just so I didn't trigger his anger. My mom says he needs to get therapy and then my dad starts calling my mom crazy saying he's going to call the cops and get her admitted. I am seriously at a loss. My mom is at her breaking point and there's only so much I can do at 19 and the eldest daughter. I don't know who to reach out to, how I'm even supposed to, I don't know what to do. My dad is going to tear our family apart if he doesn't realize what he's doing to us and himself. What do I do??!?!