Dreams involving violence, especially those involving loved ones, can be particularly distressing and often reflect deep-seated emotions or conflicts. Here are some interpretations of your nightmare:

1. Fear of Conflict: The argument with your dad may symbolize underlying tensions or unresolved issues in your relationship with him. The act of him stabbing himself could represent feelings of helplessness or fear regarding those conflicts.
2. Concern for Well-being: Seeing a loved one harm themselves in a dream can indicate worries about their mental or emotional health. It might be a manifestation of your fear that they are struggling in ways you might not fully understand.
3. Feeling Overwhelmed: Your reaction in the dream—freaking out and trying to call for help—suggests that you may feel overwhelmed by certain situations in your life. It could reflect anxieties about being unable to intervene or support those you care about in difficult times.
4. Brother's Indifference: Your brother's passive reaction might symbolize feelings of frustration regarding familial dynamics. It could represent a sense of isolation or feeling unsupported in dealing with family issues.
5. Need for Communication: The dream may serve as a reminder of the importance of open communication with your family. It can highlight the need to address any underlying issues rather than letting them fester.
6. Release of Emotions: Nightmares can sometimes be a way for our subconscious to process intense emotions. It may be beneficial to explore any feelings of anger, fear, or sadness you have in relation to family matters.

Consider reflecting on your relationship with your father and brother, and whether there are any unresolved tensions that need to be addressed. It might also be helpful to talk to someone you trust about your feelings. If the dream continues to trouble you, discussing it with a professional could provide further insight and support.