AITA for Not Letting My Sister’s Kids Use My “Toy” Room?

I (34M) am child-free and have been my entire life. I’ve always loved hobbies like building LEGO sets, collecting action figures, and even some light gaming. Over the years, I’ve turned one of the rooms in my house into a “toy room,” which is essentially my personal space filled with collectibles, intricate LEGO models, and a few rare items I’ve spent a lot of time and money acquiring.

My sister (38F) has three kids: 9F, 7M, and 5M. She’s always known I’m into this stuff and never seemed to care until recently when her family came over for a visit. Her youngest son (5M) saw the room while I was showing my brother-in-law around the house and immediately got excited. He asked if he could go in and play.

I gently told him that the room wasn’t for playing, and I’d be happy to set up some toys he could use in the living room instead. This didn’t go over well with my sister. She said I was being ridiculous and that I should let the kids “be kids” and enjoy themselves. I stood firm and explained that many of the items in that room were fragile, expensive, or had sentimental value.

Her kids were disappointed, and she accused me of being “selfish” and “not understanding how to be part of a family.” She’s since brought it up multiple times, saying I’m “hoarding toys from actual children” and making her feel unwelcome.

To be clear, I love my niece and nephews. I’ve always gotten them gifts for their birthdays and played with them when they visit. But I see my collection as more of a hobby or an art display than something for kids to handle. It’s not like I have a house full of toys and I’m refusing to share—it’s one dedicated room that I’ve spent years building up.

My parents are split on the issue. My mom thinks I could’ve “compromised” by supervising the kids in the room, but my dad sides with me, saying it’s my house and my rules. My sister’s still upset, and now I’m starting to wonder if I overreacted.

So, AITA for not letting my sister’s kids play in my toy room?