NAH.

I'm a grief counselor. Grief is complicated and messy and there's no right or wrong way to grieve. A feeling of relief is entirely normal especially in a situation where the person who died has been suffering. It's also important to remember that the relationship you have with the person who died is different than someone else's relationship, even someone in your immediate family. I see this a lot in children who have lost a parent. They can have wildly different feelings about the death because even siblings raised in the same house can have very different experiences with the same parent. You are entitled to your own thoughts and feelings about the death although as someone else suggested it may be tactful not to express them to your brother if you suspect that he would find them upsetting. The fact that you even made this post says to me that you probably don't need that pointed out to you.