I agree about the apparent normal being so disturbing to us. At its worst it is gas-lighting - trying to convince someone that their ideas are crazy, and they (the MLCer) is normal. I think we buy into it because these words are coming out of their mouths, and we loved and trusted them for such a long time.
My eldest son (an adult) put it succinctly 'Dad can do normal these days for about two hours and then the cracks start to show'. However a few years back he could only do normal for about 20 minutes tops, so that is progress, of a sort!
They absolutely have to normalise it to themselves. I really have reached the stage of eating the popcorn and watching the show unroll. The rollercoastr is amazing when you finally emotionally detach.