He tells Sully he doesn't need him and wishes he'd never made him up in the first place. Which is uncharacteristically cruel of Sam.

I didn't think this was uncharacteristic at all. Sam thinks he's essentially talking to himself, and he's not really ever that nice to himself, especially when his "self" is criticizing the way he's going about things. Think how Sam reacted to the younger version of himself who asked why Sam abandoned normal in Levee.

I also wasn't that surprised by Dean's behavior. Sully threatened Dean's view of himself and his rather skewed perspective on how much control he really had back then and has now, and anytime Dean is threatened that way, he's gets callous. It's clearly a self-defense mechanism and you can see it in early seasons too, it's just not a particularly nice one.