I feel so deeply for everyone here who is estranged. I think Peony's point about focusing on "what you do have" is very important. Not only will it bring you some joy and peace of mind, but it's more fair to the loving family who have stayed in contact and even offered support sometimes.
But I also understand the poster who said this is a bereavement. If not the loss of a person, exactly, it's the loss of a relationship. I imagine people often need time to heal and get a little past the grief before they can start paying more attention to their other, more loving relationships.
That's an interesting point about the eldest AC, Tigertooth. If I recall correctly, the eldest is usually either the most responsible child or the most rebellious. Perhaps those who CO their parents are in the "most rebellious" category.
Keffie, unfortunately, I don't think your experience is that unusual. I know someone who was dropped by her DH's relatives as soon as the funeral was over, even though they had been very close. They had rigid attitudes about "blood," etc. Since she was no longer married to their DB, they no longer saw her as "family." Sad but true.
It seems as if, in your case, there were some issues between the 2 troublemakers and your DH before he died, however. Otherwise, why wouldn't they even come to the funeral? Unfortunately, those issues may have spilled over onto you. Either way, I'm so sorry.