Anonymous wrote:She has no interest or patience for anyone who wants to say anything nice about him or memorialize any of his nice attributes in any way. As I said, I understand she is very hurt and angry at him.
Sorry for your loss, OP. I agree with the pp that YOU can memorialize him--that's not the place of the ex-wife. Have a memorial service or party, bring together the people who loved him, and honor him as you see fit. If his daughter can be included, great. If not, ask people to write or record positive memories of your brother for his daughter. (You might want to save these for your niece for when she is older and can appreciate them more.)
In the long run, being on good terms with the ex-wife will be your best bet, particularly if you want to remain close to your niece. But remember that your brother's death is not her loss--it's your loss and her daughter's loss. She can't and shouldn't be chief mourner here, as her feelings about his death are going to be very mixed. Don't hold her to a certain standard of mourning. And if you can, try to get past her inappropriate decisions about what to do with his belongings, for example. It's possible that at this point she sees your brother's death as just as another thing she and her daughter have to blame him for. She has new, additional responsibilities (being a solo parent, dealing with his estate, helping your niece work through her grief), and while it sounds like she has made some unkind decisions, I don't see that calling her on them is going to improve your relationship with her.