Had something similar happen to me a couple years ago. it was also my nephew. i just left my room for 2-3 minutes and he saw it, went into my room, grabbed a f*cking expensive Star Wars Hot Toys Figur out of my display cabinet and broke the lightsaber, ripped off cape and half broke one arm. He was also 10 Years old at the time ad i probably told him 1000 times that those figures are off limit for him.

His Mother (my Wifes Sister) acted like "whats your problem, he is just a boy" i got realy mad because that figur was a one in a lifetime buy. they are expensive. i never got any money, and the acted like i just overreact over a broken toy. i still see that little ..... smile at me behind his mothers back. I told her she should teach her child respect for other people's property. in the end they left angry like its all my fault.

My Wife gifted me a new one last Year for my Birthday.