Originally Answered: Dream of my sister trying to kill me and then framing me for her murder meaning?
You could be releasing this anxiety now that she's out of the house, and you feel like you don't have to be on your guard anymore. On the other hand, this could mean you are still afraid this situation is going to get rapidly worse until she hurts herself and others around her. You want to prepare, but you can't because you don't know what she's going to do.
If you have any pent up anger against her, or have fantasized for a moment about hurting her for revenge, this could be a self-inflicted guilt response, or it could literally be your brain trying to calculate a violent encounter with her so you can prepare yourself if it ever happens.
Your relatives lack of reaction means one or both of two things. 1) You believe you know bad things about your sister that no one else does. 2) You are self-focused in how this situation is affecting you. Not saying your selfish, the point of view could have been tested just for the duration of this dream. No one can help considering this perspective, especially when dreaming and allowing thoughts to flow freely.
The escalation of weapons used is standard form shifting, found in most dreams. It also means you fear this situation will get worse before it will get better.
Deciding that you weren't really dead was a reflexive subconscious defense to prevent you from hurting yourself any further psychologically.
Your mother's refusal to report your sister to the police, and your insistence on it, suggests that you think your sister should be held more responsible for her actions, while your mother doesn't seem to be trying to do anything about it.
When your sister slit her wrist, and declared it your fault, this means you would be willing to help your sister be free of her problems, but she won't let you. It also suggests your sister is not very keen in determining the real source of her own problems, many of which, I'm guessing, are self-inflicted.
In conclusion, this must have been horrible for you to experience. I hope your sister comes around so you can find peace. If she doesn't, try to find peace anyway.