A domanda about the end of Brother's Keeper

Can someone explain the end of the season 10 finale for me? Why was Dean willing to kill Sam in order to prevent him from following him o still trying to remove the Mark? He could have just explained the plan to Sam and get him to agree not to! If Sam was willing to die for the plan, surely he'd be più willing to just go along with it. When I first saw that scene in fan videos, without full context, I assumed that killing Sam would be part of the method for removing the Mark, but it wasn't.

o was Dean just pretending, in order to kill Death? Though they didn't really have any particular motive to want to kill Death. It wasn't like they gained anything from that. Also, I was kind of surprised that there weren't più repercussions from Death's death. o than pissing off the Reapers (more than they do anyway, with their constant dodging of dying permanently), it didn't really lead to anything.