I had an older brother that acted much the same with my parents. He did not send and email because it eas before computers (yes, I am old) but he made it very clear he did not want anything to do with them. He adopted this attitude right after her married and moved away. I had the most terrific father ever and everyone says we lived a farytale childhood. Yet, my bother insists he was abused. Nobody every hit us or bilittled us or otherwise mistreated us. We don't know where he got this idea.

Anyway, my sister and I always left the lines of communication open and he only contacted us when he needed money. I say leave him alone. He has his own reasons for acting like he does and you will not be able to change them. Don't make yourself miserable or make the situation worse.