Heartfelt compassion for you, Nan. You are not alone. A bomb has blown up in your face, and you feel like pieces of your life are scattered all over the place. You really second guess everything right now, I suspect. Frantically trying to access mental files to scan back over years and years looking for answers. This seemingly callous de-sensitization of lots of young adults seems to be getting all too prevalent. I've thought about it a lot. I also have one DS who cut me out of his life a year ago. I have tried to ponder about this, one idea I have is that it mostly seems to be 20-30 yr olds, and I wonder if that signals most of us are the baby boomers and lots of things turned upside down in the 60's, parental disdain really took on a life of its own. And we took in all this, but in fact we were not able to assimilate that into our own selves, we were still locked into believing in parental authority, respect, family loyalty, honor, etc. But I wonder sometimes if we still felt the influence from society so strongly, that we communicated this sense of entitlement and preference to our children, and they became less attached to us than generations before, hence able to 'cut us off' without deep remorse and guilt. I know that isn't the only factor, divorce has also played a big role. But other previous generations weren't raised in hothouses, families have always had alcoholism, poverty, craziness. I'm sorry for that rambling, it may not have helped anyone else but I needed to say it.
Dear heart, something concrete may have transpired, i.e. ex told some family secret but I don't actually think so. I think it may have been an emotional manipulation of DF setting himself up as the White Prince now. I admire your judgement in not doing what we all want to do, probe for information. In time, you are going to hear the truth but in the mean time, you have an opportunity for some lavish personal growth by reading and writing here, and it will get less and less urgent to have this unraveled. Take courage, all is not lost. This is a bump in the road but you can keep going forward and come out on top.