Anybody watch Divergent? Can you explain the ending?

[MichelleHW101]

I watched Divergent and liked it much better than the Hunger Game movies but I just don’t get the ending.  The group is in Dautnless headquarters, after Jeanine (Kate Winslet) is injected with the serum and stops everyone from the mind control why does Tris, Caleb, Peter, Four and his dad Marcus run away?  Why would the Dauntless leaders kill them?  Especially Marcus who’s the leader of the government?  Did Erudite actually succeed in taking over the government?  Why couldn’t they tell everyone what Jeanine did?  I mean she did mind control the Dauntless faction to completely annihilate the Abnegation faction.  And why leave her alive? It’s like she just got away with it.  And what about the other Divergents?  They just focus on the ones from Dauntless because that’s where Tris went but still.  Weren’t there any in the Amity (the peaceful) faction or Candor (the honest) faction?  And what about those two factions?  If they learned what Jeanine did wouldn’t they help the group?  And aren’t the Dauntless that were under the mind control gonna want answers?  Especially Tris’s friend Christina.  Christina’s gonna find Will dead and Tris missing.  She was of the Candor faction so I doubt she’s just gonna believe whatever she’s told.