How do I get the tenants to realize my landlord was wrong?

I’ve been living with my landlord for a bit more than 6 months. At first it seems great because the place is really nice and well decorated and furnitured, the landlord is rarely home, a cleaner come in every week, and two other tenants who live here are great. The house is also in a beautiful semi rural area.
My landlord who is in early or mid 30’s has always been rather shady. No body is sure where he’s from. He isn’t too talkative toward most people, have bunches of suspicious scars, and is rather cold and distant. He always claims he’s a translator for living, but yet we’re in a small city that is almost two hours away from nearest big city. One of the tenants once told me that he used to be in military for a long time and hinted that he have lose someone very close to him in war. They have say if you get past his barrier, he’s actually a very nice, caring, and a great friend that can be rely on.
I am not too fond of my landlord, but I love living here and since landlord was almost never home, I didn’t mind it at all.
On Saturday I and my boyfriend decided to have a party here while the landlord was gone. So we invited about ten people and have some beers and potluck and stuff but nothing crazy. Both of the tenants were very upset about the whole thing and told us to get out. Since there was so many of us and my boyfriend is really big and have a couple other guys with him, we weren’t too worried. A couple hours later, the landlord came home unexpectedly.
He end up told everyone to leave. When we tried to cool him down and tell him it will be ok, my boyfriend tried to be friendly to him by trying to be funny and put arm around him. To make whole story short, he end up attacked my boyfriend and a couple others. Then he held a knife to my boyfriend’s eye and threatened to cut his eye out if everybody didn’t leave. That’s when everyone left.
My boyfriend has a fractured sternum, bruised kidney, torn liver, and some damages to face. What really bothered me is when my landlord was doing all this, it was one of very few time when I see him actually smiling.
I’m living with my mom now. We’re trying to find a attorney because the police wrote it off as self defend.
Why is this landlord such a ass? We were trying to have some fun, be nice, and respectful then he did this to all of us. On top of everything, the tenants refused to take my side in the court and say it was my fault. Why would the tenants stand behind him on the whole subject?