How would you respond if one of your family members threatened your partner?

So we was early on in the relationship and her sister was living with us basically being able to do anything she wanted eat our food, not pay rent essentially just draining our resources also being extremely disrespectful about our rules. I was reaching my breaking point where I told her I can’t continue to live like this I was anxious depressed because I essentially felt trapped in a prison. She never did anything about her sisters behavior so I said I wanted to breakup this leads to her having a massive temper tantrum and her sister threatening to kill me. So for my personal safety I had to go back into a relationship that was becoming less and less desirable because my voice was essentially being silenced.

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3 mo
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How would you respond if one of your family members threatened your partner?
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