But what he did to get to that point, the actions he took between RotJ and TFA were very out of character every step of the way for me, and that’s pretty hard for me to accept.
I think there could be a perfectly reasonable explanation for it. Luke snapped, just as he did in ROTJ. He was able to turn away from the dark at the last moment in both cases, but there was nobody to bail him out the second time and he was dealing with a very different situation.