Have you ever been betrayed by family ?

Today my sister got caught stealing money from my mentally ill brother . My mum would often trust her to take him shopping etc or just say out to get his mind of things as my mum is of old age so doesn’t have the energy to walk around . Anyways my sister had stolen over 8k in his disability money which he had been getting over time and some money which we put on the side for him incase he ever needed it if he had to ever live on his own .

But Yh truly heartbroken how your own siblings could do such things