No, the landlord is not vicariously liable for what is tenant does. So you can not sue the landlord successfully for his tenant's actions. Call the cops every time the neighbor threatens or hits you, also, try to get a restraining order. Get a lawyer to send the tenant a cease and desist letter as well.
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I agree wit the previous response. If the abuse continues, seek a restraining order against the person committing the abuse.
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