How would you react? Okay so my older half sister (I'm 21 she's 23) just recently started seeing…

How would you react?

Okay so my older half sister (I'm 21 she's 23) just recently started seeing this guy a few weeks ago. He's super disrespectful & arrogant, for example: When he was asked to keep his voice down because everyone was sleeping at her moms house, he said "how much is this house worth? I'll pull my checkbook out & buy it so I can be as loud as I please". He says things like that then plays victim when we tell my sister we don't like him & that we don't want to be around him.