I'm really glad that your mom and dad are still spending time with your kids; I was afraid that they wouldn't. I still hope that this situation makes your mom think. She loves you so much. She has a deep investment because of her years in the organization, but I keep thinking that she loves you more.
Do you remember the disfellowshipped people that lived next door to your grandma? I never knew them because they were disfellowshipped long before I ever lived in Texarkana. Anyhow, when their adult son died I remember your mom taking them a card and a covered dish. She knew that they were disfellowshipped, but she did that anyway. Of course I am sure that her actions in that instance were at least somewhat motivated by a desire to help them return to the organization. But it still seems to suggest at least a little hope that kindness toward her own son might win out over dogmatic obedience to rules. I also remember that she was much easier on your brother than your dad was.
And as for your dad...he's a tough one. After I was disfellowshipped, though, he still continued to speak to me at work because he felt that if he ignored me completely it would look bad to our coworkers. We never talked about "spiritual" matters, but we didn't solely discuss work related thing either. And, when I was in the hospital shortly after I was disfellowshipped, he called a few times to check on me--but he thought that I was trying to get reinstated so I am sure that is what made the difference.
I do feel sorry for your parents. I know them and I know they are good people; they would not have been so good to me and put up with so much out of me if they weren't.
As you know, my close family never shunned me. Sometimes that makes it harder for me to fully empathize with those who have lost their families. Seeing your experience though is really opening my eyes to how horrible this is for all involved and makes me dislike the organization even more. You and your mom and dad deserve better than that.