MIL rearranging house

I came back from my honeymoon and my mother in law had been in my house. My husband and I had not been living together at this point. When I arrived home, artwork had been hung on the walls, my entrance tables had stuff all over it, my spare bedroom was a replicate of his old bedroom at their place and they had filled our wardrobe with his clothes, leaving no room for mine. How would you react in a situation like this?