If you only knew how close to home this hits. Many years ago I worked with a lovely man who was absent for a while. I was young and stupid. When he returned he was 'svelte'. I complimented him on his weight loss. He looked at me grimly and told me how sick he'd been. A few months later they were taking up a collection for his funeral at work.
Your story has so many lessons, about siblings not getting past childhood, about misunderstanding, about miscommunication. It's a great story. Not overplayed. Not underplayed. No tear jerking. Just raw truth.