My stepson keeps destroying my things?

My stepson (3 years old) breaks and tears up everything I own just about. He never tears up his father's stuff, just mine. He got into my display case that I keep my wedding memorabilia in and tore up my bouquet and stomped on my tiara and broke it. He wrote on my sheets with marker. My Marilyn Monroe figurines he's broken along with alot of my other stuff. When we dropped him off he told his mom I was mad at him and she asked why and he told her what he did to my sheets. She said way to go buddy and gave him a high five. I think he's being coached to ruin my stuff. I'm tired of it. Is there anything I can do because I'm about to lose my patience. My husband says he's a kid and doesn't know any better. I say otherwise. He knows what he's doing. I've talked to my stepson about it but he doesn't care. I know he's only three but something has got to give.