My own situation mirrors your's in many ways. Remember that life is indeed short and good relationships and friends are gifts that make life full. You're doing the right thing with your mom - if that's what she wants. I'm trying to make time to just visit with my parents as often as possible - nothing special....sometimes just dropping by - showing them that I'm here for them.
I suspect that the really nice folks that you grew up with at the Hall were good - not necessarily because of the religion - but because they were just really good people. The idiots in the hall - elders, elders wives, other kids - usually just wind up being....well..."idiots."
I too can feel sad when I think about things - I'm in the middle of the fading process. Or maybe it's just a general disappointment with the realities of "the Truth".