I agree that the main problem is with your BF. No doubt the family is being rude. I don't fault them (the family or your BF) for honoring someone they loved by remaining close with each other, but they also need to realize that all of them are moving on with life. To continue their relationship, they need to accept you as part of BF's life. If your BF cannot insist that they do and cannot stick up for you when they are so openly rude, then you should have a big big problem with him.
I think I told you this in your last thread, but my DH is a window and is still very close with his late wife's family. In turn, I spend time with them as I do my family and in-laws. No doubt that they are sad at their daughter's untimely passing (sometimes overwhelmingly so) and that my presence in their life is only because her's is gone. I don't even doubt that they often wish that DD was the child that DH and their daughter bore (they had no children together). Still, they've always treated me with warmth and graciousness. They honor thier daughter's memory everyday and rejoice that they and DH have found life and happiness after such a tragedy.
And if they didn't...DH would do something about it...even if it meant no longer visiting with them. Luckily, that has never been an issue or a consideration.