Is it legal for someone to destroy your belongings that's in their home if you're currently living with them?

So me and my mother have run into hard times and had to move in with her mom (my grandmother). My uncle (grandmother's son) has been also living in grandma's house for a few years as to help her with daily chores and pay a substantial part of her bills with his well-paying job. But he's since gotten tired of us being there. Grandma isn't; she loves having her kids and grandchild under her roof.

Yesterday he snapped, removed the only internet router from the house and said in a very threatening tone: "Let me catch you at that computer again & watch what happens!" He has a temper and has been known to break things in the past when frustrated. Would he be able to just destroy my computer or other belongings without any legal consequences for his actions? Apparently he thinks that the second we walked in all of our belongings became his. Could he be arrested for doing so or would this be considered a civil matter to be handled in civil court?

As a side note: i'm not complaining about the internet being gone. He pays for that so it's his right to do what he pleases with it; but to physically destroy other people's belongings doesn't sound right or even legal to me.

Also: we're in the state of Louisiana if that helps any.