AITA for demanding my brother replace expensive coins?

Me and my husband Shane share a large home near a beach – we initially bought it thinking we were going to have kids but ended up deciding against it so since we have multiple spare bedrooms and it’s near the beach, I let my siblings and their kids use the house as a holiday house for when they go on holidays. Recently my brother Tim and his 3 kids (Bessy, who is 9, Jimmy, who is 11, and Timson, who is 13) spent the weekend here while Tim’s wife was working and my husband and I were going camping.

As of recently, Jimmy has had a bit of an interest in money. He celebrated his 11th birthday last month and did not hesitate to show everyone in the family his “savings” which he accumulated from pocket money and his birthday money. I did not realise that his interest in money extended to my coin collection which I keep in one of the spare rooms, and when we got home on Sunday, I found Jimmy and Bessy playing shopkeeper with some of my previously uncirculated shillings. Jimmy bragged about the fact that he “found” my shillings, but he stopped when I told him those were rare coins and that they were actually my belongings and not his to keep.

He gave me the shillings back, and upon inspection I realised he had polished them. I asked him what he did and he said he accidentally touched them after eating without washing his hands but it was okay because he brushed them clean with soap and water. At this point I got a bit cross and tried to explain that his polishing of my rare coins made their value plummet but Tim stepped in to defend Jimmy saying “You can’t get too mad at him, he’s only 11 and he just loves money. Surely the coins can be restored.”

I was really not happy about this and explained to Tim that Jimmy removed about £200 from the value of my coin collection by doing this, and he started to get mad at me and asked whether I cared more about my coin collection or my nephew. I was not going to be berated in my own home and so I told Tim and his kids they had to vacate the house early and I was going to need an apology letter from Jimmy before I would feel comfortable having him as a house guest again.

After they left, Shane and I searched through the coin collection to make sure no other coins were vandalised and we found that a gold sovereign was missing from the collection. I called Tim and he told me that Jimmy, Bessy, and Timson were playing with it at the beach but it got lost. At this point I am furious because that coin was worth a lot of money and I said that Tim would have to replace the coins that his kids either lost or vandalised before they would be welcome in my home again. Tim told me that he didn’t have the money to do that because he needed that money to buy Jimmy a new phone and I said that I didn’t care and I would report it as theft if the coins were not replaced.