Story: My parents killed my brother-in-law (read)

My parents killed my brother-in-law. The story starts almost a year ago when my younger sister started dating the man who would be her future husband. They married when she was 17 last October. He had just turned 21. The marriage was consented by both parents.
The day before the murder, my mother and my brother-in-law got into an argument over the phone. It exculated and my mother starting threatening to kill him. I was with her when she started making the threats but I did not really think she would go through with it and told her to stop, to let the kids live their lives--my sister was five months pregnant. She got very angry at me and dropped me off at my apartment that day. There was a call from her later that night that upset me so my sister and her husband stayed the night because I was still very upset. The next day, my mother called, wanting stuff she had left at my apartment.

She was going to come over with the police. However, they showed up without the police. I stood by the door holding it closed because I knew that either she or my dad had the key. Instead of using the key, she smashed the glass on the door, causing glass to fall on me, then unlocked the door and came in. She then started beating on my brother-in-law, calling him names. My father came in seconds behind her with a rifle in his hands. Without hardly any warning at all, he came into the livingroom, turned, pointed the gun at my brother-in-law and shot him three times. My parents then walked out of the apartment and waited downstairs for the police to arrived while I stood in the kitchen screaming. They are both being charged with first degree intentional homicide but they are--I believe--going to try to do not guilty by reason of insanity. These past two weeks have been very hard for both my sister and myself. Not only did I witness the murder but since it happened in my apartment, I could no longer live there. And, since my name was all over the papers--as well as my parents'--it was difficult finding a new place.
I still do not know what to think. It seems surreal sometimes. Your parents are not supposed to kill people. But they did and have since shown no remorse for what they have done. Everything has changed and nothing is the same anymore. And it's really, really very hard for me. I have nightmares and get very angry sometimes because I don't feel that people understand what I'm going through. My sister and I are closer than we ever were after going through this event but it still doesn't change the fact that it happened and nothing's going to be the same ever again.
If you have any questions, feel free to ask.