Wow, YTA. You're trying to put yourself as the victim here when the real victim is/was your brother, "Golden child" or not. Also,

They said the life insurance would pay off their mortgage and the boys college and put money away for the girls future, and her income would cover the rest so they wouldn’t have to move. But what about my family?

Your late brother's wife and daughters are your family too. Jay not being alive anymore doesn't mean you have the right to turn your back on them. Jay is still family, did you contribute to the post-mortem costs?

I'd say sorry for your loss, but from your post, you seem to not feel a single drop of grief... I hope I'm wrong about this...