Susan Grey died of Hiccups.
Sandrah Oh's character was literally attacked by the hospital when an icicle the size of a fishing pole fell off the awning above the front door to admitting and skewered her.
But it's more so the emotional grinder these poeple have been going though than the actual body count.
As far as Private Practice is concerned, I'm not sure what's worse when Violet's psycho stalker broke into her house and c-sectioned her to steal her as yet unborn baby (AND THEY STILL HAVEN'T MOVED HOUSE!) or the half season that dealt with Xander form Buffy the Vampire Slayer raping Charlotte. Oh, spoilers, but Pete bought the farm in the first episode this season, he had a heart attack while jogging and died in a ditch. Apparently the entire process took hours. He's just lying there listening to his body giving out, while everyone is screaming that he's a dead beat who's abandoned his family because it seemed like he's skipped the country to avoid jail for doing something heroic.
No one has a happily ever after in the Greys Anatomy Universe.