I am new to this site, my daughter(11) was diagnosed with CD last October, right after she started middle school. I had known something was wrong for 2 years but no one listened until she started losing a lot of weight and wasn't growing. She has had 2 remicade infusions and has gained almost 10 pounds, now we just need her to get taller so she isn't the smallest. Her energy level has increased ten fold, though she has some nausea. I felt sorry when I read your comment, It isn't that surprising when a stranger makes an obnoxious comment, but when your own family does you question, how are we related? trust me i can totally relate to that feeling, and it is very disheartening. my theory is that people are made up of sensitive (caring, understanding, dynamic) and insensitive, (out for themselves, incapabale, thoughtless). sensitive people only make up about twenty percent of the population, which is why the world is such a friggin mess! my daughter is sensitive, and sweeter and much smarter than anyone i know, for real...and cool!
I think you are sensitive too, so the best thing you can do is limit time with your brother, and yes, call him on his insensitivity, even though it won't change him, it will make you feel better to release your frustration about his attitude.
surround yourself with great people if you can find them...I'm still searching, but i have a few at least!