<human>: So my cousin rents out our basement, and me my father and mother live upstairs, my cousin isn't on the lease.

My cousin started dating this girl that is 19, shortly after she moved in downstairs with him without permission and she is jobless and pays no rent.

my cousin and his girlfriend fight constantly and both have anger issues, they get drunk on the weekends and it becomes explosive, they hit each other, scream, drove drunk, my cousin tries to fight my dad and everyone else and he is the most stubborn person I've ever met.

My dad is sick of their shit and told him she can't be here when he isn't and they can't fight like that every weekend (a month straight),my cousin gets very irritated calls my dad an ass hole says he can have his girlfriend over whenever he wants and doesn't have to move out and doesn't give a shit about anybody but himself in general.

He has gotten the cops phoned twice, arrested once, punched and kicked two holes in the wall, fought my dad and my uncle, verbally abused and threatened me, my dad, his step father, his mom, his brother and his girlfriend.

we seriously have no idea how to handle this, any thoughts welcome.

Summarize the given text in a few sentences.
<bot>: Cousin is an asshole does whatever he wants, fights, breaks shot, and is disrespectful, what should we/can we do.