The source is the movie. Its very clear that's what happens once you figure out what Ben is asking Han for help with. He's not asking him for help coming back to the light. He's asking him to help him kill him. That's why Ben isn't shocked by it. He was asking for Han to do it for him. Its a very Snape and Dumbledore type of situation. What's on the surface isn't really what's going down. It wasn't obvious during my first viewing, but it was very clear my second time around once I knew what was going to happen. As it turns out, Han stabs first too!
As far as Leia and Chewie not exchanging anything, I think Chewie was still really effected by the whole situation and once his duties of getting them home were accomplished, he just needed some alone time to grieve and take everything in. Plus Leia already knew thanks to her limited Force powers.
Still not convinced Rey is Luke's daughter however. She was definitely old enough to remember her father, no matter what name he was going by. So she should have said "Dad?" or something when Luke turned around. Unless, of courses, she too never knew her father and that was her mother's grave Luke was standing over.