Mortis

Obi wan had to watch Anakin and Ahsoka go dark or Sith. He has had his master killed by the sith, his grandmaster is now a Sith. He has had to deal with his lineage being a Sith or killed by one while remembering it, as Ahsoka and Anakin do not remember being one themselves. Anakin was lucky to not remember, but later when he does become one obi wan has to deal with it again, except its permantent.